Ask anyone - why do we eat Matza on Pesach? Invariably you will hear one of the two following answers: *
To remind us of the 'poor man's bread' that we ate when we were slaves in Egypt ['lechem oni'];
[As we say in the Haggada - "ha lachma anya..."] *
Because we left Egypt in haste and our dough didn't have time to rise ['chipazon'].
[As we say in the Haggada - "Matza - al shum ma? al shum she-lo hispik betzeikam le-hachmitz..."]
So, which reason is correct?
In the following shiur, we uncover the biblical roots of these two reasons in Parshat Bo - in an attempt to better understand and appreciate why we eat matza on Pesach.
In Parshat Bo, we find two Biblical commands that relate to eating matza:
In relation to korban Pesach, we are instructed to eat matza & maror together with the meat of this offering. [See Shmot 12:8.]
In relation to "chag hamatzot", we are instructed to eat matza (and not eat chametz) for seven days. [See Shmot 12:15-20 and 13:2-8.]
In Part One of our shiur, we study these two sources to show how (and why) each of these two mitzvot stems from a totally different reason.
In Part Two, we study the intricate manner of the Torah's presentation of these two mitzvot - and together with some historical considerations, we will explore an underlying theme that may tie these two separate reasons together.
In the middle of Parshat Bo (right before the story of the Tenth Plague), God instructs Moshe concerning several mitzvot that Bnei Yisrael must keep - more specifically, the laws of the korban Pesach (see 12:3-14) and a commandment to eat matza for seven days (see 12:15-20).
[This section (12:1-20) is better know as "Parshat ha-Chodesh", as it is read on the shabbos prior to Rosh Chodesh Nisan.]
As both of these mitzvot relate in some manner to eating matza, we begin our shiur by reviewing their definitions in regard to how they are to be kept in future generations:
Definition: Each year we are commanded to offer a special korban on the afternoon of the 14th of Nisan, and eat the korban on that evening, together with matza & maror; while thanking God for our deliverance from 'makkat bechorot'.
(See 12:24-27, based on 12:8-14)
Reason: Because God 'passed over' the houses of Bnei Yisrael on that evening when He smote the Egyptians (see 12:26-27). As we eat the korban, we are supposed to explain this reason to our children.
Definition: To eat matza (& NOT to eat chametz, own it, or even see it) for seven days, from the 15th to the 21st of Nisan.
(See Shmot 13:2-8, based on 12:15-20.)
Reason: To remember the events (and their miraculous nature) by which God took Am Yisrael out of Egypt. (See Shmot 12:17 and 13:8.)
Even though these holidays 'overlap' on the night of the fifteenth of Nisan and both holidays include eating matza; each holiday serves a different purpose. By offering the korban Pesach we thank God for saving us from the Tenth Plague. In contrast, on Chag Ha-matzot we remember leaving Egypt into the desert, and hence our freedom from slavery.
[Note that each holiday has ample reason to stand alone.]
With this background, let's examine the purpose for eating matza in each mitzvah. Clearly, on "chag ha-matzot" [the name for the holiday when we eat matza for seven days] - eating matza for seven days is presented as the primary mitzvah:
"Seven days you shall eat MATZA, even on the first day you shall rid yourselves from any unleaven in your houses..." (Shmot 12:15, see also 13:2-8).
As we shall soon explain, by eating matza (and not eating 'chametz') during those seven days, we remind ourselves of how God helped us when we left Egypt.
In contrast, eating matza with the korban Pesach is presented in a secondary manner, while the primary mitzvah is to eat the meat of the korban:
"And you shall eat the meat on this night, roasted on fire with MATZOT, together with bitter herbs..." (Shmot 12:8).
[Review from 12:3-13, noting how most of these psukim deal with how the korban is to be eaten, while matza is presented in a very secondary manner.]
Unfortunately, the Torah is not very specific in regard to WHY the Korban Pesach should be eaten with matza. It simply states in 12:8 to eat the meat roasted, together with matza & maror, without explaining why.
On the other hand, in regard to eating matza for the seven days of chag ha-matzot, the Torah is much more explicit:
"And you shall keep the (laws regarding) MATZOT, for on this very day I have taken your hosts out of the land of Egypt..." (see Shmot 12:17, see also 13:3!).
This pasuk suggests that eating matza for seven days will cause us to remember that God took us out of Egypt. But why should eating matza cause us to remember those events?
To understand why, we must return to the story of the Exodus in Chumash, and follow the narrative very carefully to show why 'eating matza' would remind Bnei Yisrael of the Exodus.
Contrary to the popular understanding, Bnei Yisrael had plenty of time to prepare for the Exodus. After all, already two weeks before the Tenth Plague, Bnei Yisrael had already received early warning (see Shmot 12:1-13). Furthermore, Moshe had already advised them to be ready to 'borrow' from their Egyptian neighbors the necessary gold & silver and clothing for their journey (see 11:1-3!). However, even though they had plenty of time to prepare, they were also in no special hurry to leave on the evening of the 15th of Nisan. In fact, Bnei Yisrael were under a specific directive to remain in their homes that entire evening:
"And Moshe told the leaders of Israel: Everyone should take a lamb... and none of you shall leave the entrance of your houses UNTIL THE MORNING" (see Shmot 12:21-22).
Hence, Bnei Yisrael most likely assumed that they would not be leaving Egypt until sometime the next morning. Considering that they were planning to embark on a long journey into the desert (see 11:1-3, read carefully), the people most probably prepared large amounts of dough on the previous day, with the intention of baking it early on the morning of the 15th of Nisan (before their departure). [The fresher the bread, the better!]
However, due to the sudden nature of the events that transpired that evening, these original plans changed. Recall how the Egyptians (after realizing the calamity of the Tenth Plague), rushed the Hebrews out of their homes. Pharaoh demanded that Moshe lead his nation out to worship their God (see 12:29-32), in hope that the sooner they would worship their God, the sooner the Plague would stop, see 12:33 /and 5:3!). The Egyptians were so eager for them to leave that they willingly lent their belongings.
It was because of this 'rush' that Bnei Yisrael didn't have time to bake their 'fresh bread' as planned. Instead, they quickly packed their bags and took their dough ('and ran'):
"[So] Bnei Yisrael carried their DOUGH before it had time to rise ['terem yechmatz'], as they wrapped with their garments and carried it over their shoulders.
[See Shmot 12:34.]
Two psukim later, the Torah tells exactly what Bnei Yisrael did with this dough. After setting up camp in Succot, on their way towards the desert (see 12:37-38), we are told:
"And Bnei Yisrael baked their DOUGH that they took out of Egypt as MATZOT, for it had not risen ['ki lo CHAMETZ'], for they were EXPELLED from Egypt, and they could not wait [in the their home to bake the dough properly], nor had they prepared any other provisions [and hence the only bread they had to eat was from this dough]" (see 12:39).
[This seems to be the simplest translation of this pasuk (see JPS). Note, however, that Ramban explains this pasuk in a different manner. The reason for this is discussed in the further iyun section.]
In this manner, everyone who left Egypt shared a common experience. As they set up camp on their way to the desert (the first time as a free nation) everyone shared the common predicament of: no bread; 'lots of dough'; and only makeshift methods for baking it. Therefore everyone improvised by baking their dough as thin matzot on makeshift 'hot-plates'.
This background explains the first instruction that Moshe Rabeinu commanded Bnei Yisrael on that momentous day:
"And Moshe said to the people: REMEMBER THIS DAY that you have LEFT EGYPT from slavery, for God has taken you out with an outstretched hand - you shall not eat CHAMETZ. You are leaving in the month of the spring [therefore] when you come in the Promised Land... on this month EAT MATZA FOR SEVEN DAYS... you shall not see or own CHAMETZ in all your borders. And you shall tell you children on that day, it was for the sake of this [MATZA] that God took us out of Egypt..." (see Shmot 13:2-8, read carefully!).
In other words, the next year, by eating matza (and not owning any chametz) this generation would remember this special experience together with the miraculous events of the Exodus. To preserve this tradition (and message), the Torah commands all future generations as well to eat matza for seven days, while telling over these events to their children (see again Shmot 13:8).
In a shorter form, this is more or less the reason that we cite in the Haggada when we explain why we eat matza:
"MATZA... AL SHUM MA? This matza that we eat, for what reason (do we eat it)? - For the dough of our forefathers did not have time to become leaven when God the King of all kings revealed Himself and redeemed us, as it is stated (followed by the quote of Shmot 12:39)."
This certainly provides us with a logical reason for the commandment to eat matza for the seven days of "chag ha-matzot", but it certainly doesn't explain why Bnei Yisrael were first commanded to eat matza with the Korban Pesach BEFORE they left Egypt (see again 12:1-8). It simply wouldn't make sense for God to command Bnei Yisrael to eat matza in Egypt with the korban - to remember how they left Egypt!
Therefore, there must be an independent reason for eating matza with the korban Pesach, unrelated to the events that transpired when Bnei Yisrael left Egypt
To find that reason, we must return to Parshat ha'Chodesh, and consider the thematic connection between the mitzva to eat matza and all of the other mitzvot that accompany the Korban Pesach.
Certainly, the primary purpose of offering the Korban Pesach in Egypt was to sprinkle its blood on the doorposts to save Bnei Yisrael from the Tenth Plague (see 12:12-13). However, this commandment also included several other special laws that focus primarily on how this offering was to be eaten by its owners.
This in itself is noteworthy, for one would expect that a korban (an offering) set aside for God would be forbidden for human consumption, as is the case in an OLAH offering.] Yet, in regard to the Korban Pesach, eating this korban seems to be no less important than the sprinkling of its blood (see 12:3-11). Let's take a closer look at these special laws.
First of all, note how it was necessary to carefully plan this 'dinner' in advance:
"Speak unto all the congregation of Israel -On the tenth day of this month everyone must take a lamb, according to their fathers' houses, a lamb for a household; and if the household be too little for a lamb, then shall he and his neighbor next to him shall take one according to the number of the souls; according to every man's eating you shall count them for the lamb... (see Shmot 12:3-4)
Clearly, this was supposed to be a 'family meal' (see 12:3), and planned well in advance. Now, let's consider the cuisine.
" And they shall eat its meat on that night:
* roasted over the fire
* with MATZA
* with MAROR (bitter herbs)
* Do not eat it raw (uncooked)
* [nor can you eat it] cooked in water
* eat it only roasted,
its head, legs, and entrails, (together)
* No 'leftovers', anything left over must be burnt.
And this is how you should it eat it:
* your loins girded
* your shoes on your feet
* your staff in your hand
* and you shall eat it in haste [CHIPAZON]
it is a PESACH [offering] for God." (Shmot 12:7-11)
As you review these psukim, note once again how eating matza is only one of many other instructions that go along with how this korban is to be eaten. Let's begin our discussion with some of the 'other' laws; afterward we'll return to the matza.
The law that no meat can be left over relates once again to the special atmosphere of this evening. When someone knows that any leftovers 'go to the garbage', it is more likely that he will eat to his heart's content and enjoy the meal (ask any "Yeshiva bachur"). If it was permitted to save the meat, then people would refrain from eating to their heart's content, preferring to save some of the meat for another meal (ask any poor man).
Coming to the meal fully dressed, and eating with eagerness and readiness, certainly would make this evening more memorable. [Remember as well that in ancient time a staff ("makelchem be-yedchem") is not necessarily a walking stick for the aged, but rather a sign of importance.]
It also goes without saying that lamb is most tasty when barbecued, as opposed to being boiled in water (ask anybody).
With this background, let's consider the wider picture:
A family meal - planned well in advance,
by invitation only,
fresh lamb - well done, roasted on an open spit
(roasting is much most tasty than cooking)
with fresh pita ('eish tanur' style), i.e. matza
with a spicy salad (bitter herbs), i.e. maror
no leftovers allowed
everyone coming well dressed (best attire)
eating it with readiness, zest, excitement ('chipazon')
Any of us who have attended a formal dinner should not be surprised by these laws, for this seems to be their primary intention - to create a full fledged 'shabbos table' atmosphere.
Consider the circumstances. A nation of slaves, now about to become free, and ready to embark on a momentous journey to Har Sinai and then to the Promised Land. Certainly, we want this to be an 'evening to remember', and hence 'only the fanciest restaurant' will do!
[Recall as well that it would not be often that slaves could afford to eat 'fleishigs' for dinner.]
Our main point is that the PRIMARY reason for all of these special laws was to assure that every family would participate in a formal meal, in order to make this a memorable evening. Therefore, only the best meat, cooked in the best manner, with bread and salad; with the eager participants in their best attire.
With this in mind, let's return to consider the reason for eating matza at this meal.
Considering our discussion thus far, it would have made more sense to enjoy the korban with a fresh 'chametz' bun, rather than simple 'matza'!
To appreciate why, let's return to our analogy of 'going out to eat' to celebrate an important occasion. Now the question becomes: What restaurant would be most appropriate?
Will it be Chinese? Italian? French?
In the case of korban Pesach, the best way to describe the menu would be - 'anti-Egyptian'!
Not only does God want Bnei Yisrael to enjoy a family meal on this important evening, He also wants this meal to carry a theme. The menu should not only be 'formal', but it should also carry a 'spiritual message'. [For those Americans on the list, just ask your neighbors why turkey is traditionally served for Thanksgiving dinner.]
Let's consider the menu.
As we explained, eating meat is in itself special. But why specifically lamb? Let's explain why eating lamb would be considered 'anti-Egyptian
Recall when Yaakov and his sons first went down to Egypt, Yosef was embarrassed by their profession, that they were shepherds, for anyone who raised sheep was a 'to'eva' [an 'abomination'] to Egyptians. (See Breishit 43:32.)
Furthermore, when the Plagues began, Pharaoh first agreed that Bnei Yisrael could offer their korbanot in Egypt, but not in the desert. To this offer Moshe replied, should Am Yisrael offer 'to'evat Mitzrayim' [an abomination to the Egyptians] in Egypt, would they not be stoned? (See Shmot 8:22.)
From that interchange, it becomes quite clear that offering a 'lamb' would be antithetical to Egyptian culture. Rashi's commentary on this pasuk seems to imply that a 'lamb' was considered a type of a god to the Egyptians, and hence offering a 'lamb' in Egypt would be a desecration in their eyes. [Sort of like burning someone's national flag. See Ramban 12:3!]
[Note Ibn Ezra (on Shmot 8:22) quotes a Kaarite who explained that a 'lamb' was the symbol of the god who controls their land. He himself argues that it was not just a lamb, but any type of animal, for he claims that the Egyptians were vegetarians.]
[One could also suggest an 'astrological' explanation that relates to the fact that the Nile (Egypt's source of water) reaches its highest level in the spring during the zodiac of 'taleh' [a lamb, see Nile mosaic in Tzipori!] See also a similar explanation in Sefer Ha-toda'a by Eliyahu Ki-tov, re: Nisan (page 14).]
Therefore, burning a lamb, complete with its head, and legs and entrails, etc. on an open spit (see Shmot 12:9), and then eating it, would serve as a sign to Bnei Yisrael that they are now free from Egyptian culture, and its gods.
As we explained, the primary reason for eating matza would be no different than having rolls at a cook-out. But eating specifically matza could be considered once again symbolic. The simplest reason would be simply to remind Bnei Yisrael that on this evening God is taking them out of slavery. As 'matza' is the typical bread of a poor-man, or a slave, it would be most fitting to eat the meat together with this style of bread.
[This would reflect our statement of "ha lachma anya" that we say at the beginning of the Haggada.]
This doesn't mean that a poor-man's bread tastes bad. It is merely a simple style of bread that can actually taste good!
However, one could also suggest that 'chametz' itself may have been a symbol of Egyptian culture. It is well-known among historians that the art of making leaven was first developed in Egypt, and it was the Egyptians who perfected the process of 'bread-making'.
[See 'On Food and Cooking -'The Science and Lore of the Kitchen' - by Harold McGee / Page 275 based on archeological evidence, raised bread began in Egypt around 4000 BCE. On page 280 then beer froth was eventually used as first yeast. And page 615 bread-making became refined with invention of ovens around 3000 BCE in Egypt.]
Similarly, eating bitter herbs with the korban certainly makes the meat 'tastier' - but why specifically bitter herbs rather than sweet ones? Like matza, one could suggest that the reason would be to remind us on this evening of the bitterness of the slavery that we are now leaving. In fact, this is exactly what we explain in the Haggada in the section "MAROR - AL SHUM MA".
[One could also explain that the reason for eating the korban 'well dressed' and in hurriedness (even though Bnei Yisrael would not be leaving until the next morning) was to emphasize the need be 'ready & eager' for their redemption.]
In this manner, all of the mitzvot relating to Pesach Mitzrayim can relate to both the need to make this a memorable evening, with a formal family dinner etc.; but at the same time, every action also carried a symbolic function as well. This evening was to leave a lasting impression on its participants, in order that they would pass on this memory to their children and grandchildren. It had to be special!
In summary, we have shown how there may be two totally independent reasons for eating matza on the night of the fifteenth of Nisan: *
One matza - 'lechem oni', poor man's bread - is to be eaten with the korban Pesach, in order to make this korban tasty, but at the same time to remind us to thank God for being saved from Makkat Bechorot & slavery. *
The second matza - "bread that was made in haste", 'chipazon' - is an integral part of the mitzva of chag ha-matzot (eating matza for seven days) which we eat in order that we remember the events of how God took us out of Egypt.
In Part Two we will search for a deeper connection between these two reasons for eating matza.
In Part One, we offered two reasons for eating matza with the Korban Pesach: Either to remind us of the hardships of slavery (similar to the reason for why we eat 'maror'); or to remind us of the need to reject Egyptian culture as a pre-requisite for redemption (similar to the reason for why we sacrifice a lamb).
If the following shiur, we will pursue this second line of reasoning, and apply its logic to help explain some of the peculiar laws of "chag ha'matzot" [i.e. the commandment to eat matza (and not eat chametz) for seven days].
Let's begin with the very pasuk in Chumash that appears to explain the reason for "chag ha'matzot":
"And Moshe said to the people: REMEMBER THIS DAY that you have left Egypt...- you shall not eat CHAMETZ....
[therefore] when you come in the Promised Land... EAT MATZA FOR SEVEN DAYS... you shall not see or own CHAMETZ in all your borders... " (see Shmot 13:2-8).
This commandment implies that by eating matza (and not eating chametz) for seven days, we will remember the events of the Exodus. In Part One of our shiur, we explained how (and why) eating matza would remind us of that experience.
However, based on that explanation, it would have made more sense for Moshe to say: "Remember this day... by eating matza". Instead, he commands them to remember this day by not eating chametz!
Furthermore, from the laws that follow, it seems like the Torah puts a greater emphasis on the prohibition of "chametz", more so than of the obligation to eat "matza". It also seems rather strange that the Torah would forbid not only eating chametz, but also owning or seeing it - if the only purpose of these prohibitions was to ensure that we eat matza.
Finally, there doesn't appear to be any obvious reason for the need to observe this holiday for seven days.
Therefore, it would be difficult to conclude that all of these laws stem merely from the 'incidental' event of Bnei Yisrael baking matza at that time because they were 'rushed out' of Egypt.
However, if we understand chametz as symbolic of Egyptian culture, then many of these details begin to make sense. To explain how, we must return to Yechezkel chapter 20; and our discussion in last week's shiur on Parshat Va'era.
Let's quote once again from Yechezkel's rebuke of the elders of Yehuda, as he reminds them of the behavior of their forefathers - PRIOR to Yetziat Mitzraim:
"On the day that I chose Israel... that same day I swore to take them out of Egypt into a land flowing with milk and honey... And I said to them [at that time]: Each man must RID himself of his detestable ways, and not DEFILE ('tum'a') himself with the fetishes of Egypt - [for] ANI HASHEM ELOKEICHEM . But, they REBELLED against Me, and they did not OBEY me, no one rid himself from his detestable
In other words, God had called upon Bnei Yisrael to rid themselves of their 'avoda zara', i.e. their Egyptian culture, BEFORE the redemption process began.
Unfortunately, Bnei Yisrael did not 'listen', and hence deserved to be destroyed! Nevertheless, God saved Bnei Yisrael, Yechezkel explains, for the sake of His Name: "va-a'as lema'an shmi, levilti hachel le-einei ha-goyim" (see 20:9).
This background helped us understand the need for "korban Pesach" in Egypt. This offering gave Bnei Yisrael one last chance to show their loyalty to God prior to 'makkat bechorot'.
[The word 'pesach' - the name of this korban, reflects this purpose, as God must 'PASS OVER' the houses of Bnei Yisrael (who otherwise deserve to be punished (see 12:27).]
To show their rejection of Egyptian culture, Bnei Yisrael were instructed to offer a lamb and eat it with matza (instead of chametz), due their symbolic nature.
[For a similar explanation that shows the connection between chametz and Avoda Zara, see Rav Kasher in Torah Sheleima vol #19, miluim #20.]
This can explain why 'chametz' becomes such a central theme when these events are commemorated in future generations. For example, not only must the korban Pesach of future generations must be eaten with matza, but one is also prohibited from owning 'chametz' before he can offer that korban:
"Lo tishchat al CHAMETZ dam zivchi" - "You shall not offer the Korban Pesach with chametz still in your possession" (see Shmot 23:18 and its context from 23:13-20).
If indeed chametz is symbolic of Egyptian culture, then it makes sense that one can not offer this korban, without first showing his rejection of that culture. When we offer the korban Pesach, we must remember not only WHAT HAPPENED, but also WHY God saved us, i.e. for what purpose!
To help concretize these sentiments of teshuva, a symbol is required. Hence, the korban Pesach - the 'korban Hashem' (see Bamidbar 9:7 and context) - is not just an expression of thanksgiving but also a DECLARATION of loyalty; - a willingness to obey; - a readiness to fulfill our Divine destiny.
Furthermore, in Parshat Re'eh, when Moshe Rabeinu explains the laws of the Pesach to the generation that is about to enter the Land, he reminds them:
"Keep the month of the spring, and offer a korban Pesach... You shall not eat any CHAMETZ with it, instead for the seven days [afterward] you shall eat MATZA - 'lechem oni', because you left Egypt in a hurried manner - IN ORDER that you remember the day that you left Egypt for every day of your life" (see Devarim 16:1-3).
This source also suggests that the matza that we eat for seven days relates directly to the korban Pesach, and hence it makes sense that they would share a common reason.
This interpretation can also help us understand why God's original commandment to Moshe to tell Bnei Yisrael about "chag ha-matzot" (in 12:15-20) was recorded 'pre-maturely' (i.e. before they ever left Egypt) - immediately after the laws of korban Pesach (see 12:11-15).
After instructing the nation to offer korban Pesach in every future generation (see 12:14), the Torah records the laws prohibiting 'chametz' for the next seven days. Even though eating matza for those seven days reminds us of how we left Egypt, the prohibition of 'chametz' reminds us of how must reject 'avoda zara' in order to be deserving of future redemption. This can also explain yet another difficult pasuk in Parshat ha'Chodesh:
"Seven days you should eat matza, but EVEN ON THE FIRST DAY you must REMOVE ALL CHAMETZ from your houses, for whoever eats chametz on these SEVEN days, that person shall be cut off from the nation of Israel" (see Shmot 12:15).
Chazal understand that 'yom ha-rishon' refers to the 14th of Nisan (not the 15th), i.e. at the time when the Korban Pesach is offered. This makes sense, for one must rid himself from the symbol of Egyptian culture before offering the korban Pesach. [Note as well Shmot 23:18 - "lo tishchat al chametz dam zivchi"!]
The reason for Chag Ha-Matzot now becomes clear. Our declaration of thanksgiving when offering the korban Pesach is meaningless if not accompanied with the proper spiritual preparation. Just as Bnei Yisrael were commanded to rid themselves of their 'avoda zara' in anticipation of their redemption, future generations must do exactly the same when they commemorate those events. By getting rid of our chametz in preparation for Korban Pesach, we remind ourselves of the need to first cleanse ourselves from any corrupt culture that we may have adopted.
From this perspective, the matza that we eat for seven days, and the matza that is eaten with the korban Pesach both serve as powerful reminders that Bnei Yisrael must become active and faithful partners in any redemption process.
Based on the above shiur, we can explain why we invite Eliyahu ha-navi to the seder (after we finish our last 'kezayit' of matza) to remind us of the need to perform teshuva in preparation for future redemption (see Mal'achi 3:23-24). It also explains why we read these psukim (that form the final message of the Neviim in Tanach) for the Haftara of Shabbat Ha-gadol, in preparation for Pesach.
An important phrase that the Torah uses in its presentation of the laws of chag ha-matzot provides further support for this approach. Recall the original pasuk in which the Torah provides the reason for chag ha-matzot:
"And you shall keep [the laws] of the matzot, for ON THIS VERY DAY [BE-ETZEM HA-YOM HA-ZEH] God has taken your hosts out of the land of Egypt..." (see Shmot 12:17).
It is not often that the Torah employs this phrase "be-etzem ha-yom ha-zeh", and when it does, it always marks a very important event.
In relation to Yetziat Mitzrayim we find this very same phrase mentioned two more times at the conclusion of chapter 12, as the Torah recaps the events of Yetziat Mitzraim - in the context of God's fulfillment of His promise to Avraham Avinu at Brit bein Ha-btarim:
"And the time of Bnei Yisrael's stay in Egypt was 400 years and 30 years, and it came to pass after 430 years - ON THIS VERY DAY [be-etzem ha-yom ha-zeh] all of God's hosts were taken out of Egypt..." (see 12:40-41, see also 12:51!)
It is not by chance that we find specifically this phrase "be-etzem ha-yom ha-zeh" in relation to God's fulfillment of brit bein ha-btarim. In Sefer Breishit, we find this same phrase in two instances, and each relating to the fulfillment of a 'brit' between God and man. The first instance was God's 'brit' with Noach:
"And I shall keep My covenant with you, and you will enter the ark, you and your sons and wife..." (see Breishit 6:18).
Then, when Noach actually enters the ark, the Torah uses this phrase when informing us how God kept His covenant:
"Be-etzem ha-yom ha-zeh - on that very day, Noach and his sons and wife... entered the ark..." (see 7:13).
Similarly, when God enters into a covenant with Avraham Avinu concerning his future, better known as BRIT MILA; God promises:
"And I shall keep My covenant between Me and you and your offspring an everlasting COVENANT to be Your God... this is [the sign] of My covenant that you shall keep, circumcise every male child..." (see Breishit 17:7-10 and its context).
Then, when Avraham performs this mitzva, the Torah once again uses this phrase when informing us how Avraham kept His part of the covenant:
"be-etzem ha-yom ha-zeh - on this very day - Avraham was circumcised and his son Yishmael..." (see 17:26, & 17:23).
Considering that these are the only times that we find this phrase in Sefer Breishit, and both relate to the fulfillment of a major covenant between God and man; when we find that the Torah uses this phrase in Sefer Shmot, we should expect that it too relates to the fulfillment of a covenant. Clearly, this phrase in both Shmot 12:17 and 12:41 must relate to God's fulfillment of Brit bein ha-btarim. Hence, one can suggest that its use in 12:17 in relation to the mitzva to eat matza for seven days relates to Bnei Yisrael's need remain faithful to its side of the covenant with God. Based on the psukim quoted above from Yechezkel, the thematic connection is rather obvious. If Am Yisrael is truly thankful for their redemption from slavery, they must show their dedication by totally removing themselves from the 'avoda zara' of Egypt.
Note as well that the phrase of be-etzem ha-yom ha-zeh also appears in Sefer Vayikra, once in relation to Shavuot (see 23:21) and twice in relation to Yom Kippur (see 23:28-30). [Note that it does not appear in relation to any of the other holidays in Emor!]
On could suggest that here again this relates to 'britot'; Shavuot relating to 'brit sinai' - the first luchot, and Yom Kippur relating to 'brit sinai' - the second luchot. See TSC shiur on Parshat Ki Tisa on the 13 midot of rachamim.
One last mention of this phrase is found at the end of Parshat Ha'azinu in relation to 'brit Arvot Moav'.
Finally, we find this phrase in Yehoshua 5:11, mentioned as Bnei Yisrael performed both BRIT MILA & KORBAN PESACH when they crossed the Jordan River and began conquest of Eretz Canaan! Again the fulfillment of yet another stage of both brit mila and brit bein ha-btarim.
See Ramban on Shmot 12:39, how he explains that Bnei Yisrael's original intention was to bake matza, the rushing only caused them to bake the dough matza on the road instead of in their homes in Egypt. Even though this does not appear to be the simple pshat of the pasuk, it stems from the Ramban's approach of yesh mukdam u-me'uchar, and hence God's commandment to Moshe in 12:15-20 was indeed given before Bnei Yisrael left Egypt, and hence applied to the first generation as they left Egypt as well!
It should be noted that since we don't offer a Korban Pesach now of days, we obviously cannot fulfill the mitzva of eating matza with it. Therefore, the matza that we make the 'bracha' of 'achilat matza' on at the Seder night is for the second reason, based on the pasuk "ba-erev tochlu matzot" (see Shmot 12:17-18, and its context). On the other hand, to remember this matza, we eat an extra piece of matza together with maror - "zecher le-mikdash ke-Hillel" - to remember how this mitzva was fulfilled during the time when the Temple stood.