That bread, which our fathers ate in the land of Egypt. The Mitzva of eating Matza  was given to the children of Israel even before they departed Egypt, relating to the future exodus, which was to be in haste. It follows that the Mitzva of eating a Matza was given to them while they were still enslaved, and the aim of the Mitzva was for the time of redemption, since then they departed in haste.
This is why we like to remember the eating of Matzas in Egypt even today, since we, too, are as when we were enslaved abroad. Also, with this Mitzva, we aim to extend the redemption that will happen soon in our days, Amen, just as our fathers ate in Egypt.
This year – here… next year – free. It is written above that with the aim of this Mitzva we can evoke the guaranteed redemption, destined for us, as in the Mitzva of eating the Matza of our fathers in Egypt.
We were slaves… It is written in Masechet Pesachim (p 116), “Begins with denunciation, and ends with praise.” Concerning the denunciation, Rav and Shmuel were in dispute: Rav said to begin with “in the beginning, our fathers were idol worshipers,” and Shmuel said to begin with “We were slaves.” The practice follows Shmuel.
We need to understand this dispute. The reason for “beginning with denunciation and ending in praise” is, as it is written, “as far as light excelleth darkness.” Hence, we must remember the issue of the denunciation, that through it we acquire thorough knowledge of the mercies of the Creator with us.
It is known that our whole beginning is only in denunciation, since “absence precedes presence.” This is why “a wild ass’s colt is born a man.” And in the end, he acquires the shape of a man. This applies to every element in Creation, and this was so in the rooting of the Israeli nation, too.
The reason for it is that the Creator elicited Creation existence from absence. Hence, there is not a single creation that was not previously in absence. However, this absence has a distinct form in each element in creation, because when we divide reality into four types: still, vegetative, animate, and speaking, we find that the beginning of the still is necessarily complete absence.
However, the beginning of the vegetative is not complete absence, but merely its former degree, which, compared to itself, is considered absence. And in the matter of sowing and decay, which are necessary for any seed, it is received from the shape of the still. Also, it is the same with the absence of the animate and the speaking: the vegetative form is considered absence, with respect to the animate; and the animate form is considered absence, with respect to the speaking.
Hence, the text teaches us that the absence that precedes man’s existence is the form of the beast. This is why it is written, “a wild ass’s colt is born a man,” as it is necessary for every person to begin in the state of a beast. And the writing says, “Man and beast Thou preserves, O Lord.” And as a beast is given all that it needs for its sustenance and the fulfillment of its purpose, He also provides man with all that is necessary for his substance and the fulfillment of his purpose.
Therefore, we should understand where is the advantage of man’s form over the beast, from the perspective of their own preparation. Indeed, it is discerned in their wishes, since man’s wishes are certainly different from those of a beast. And to that extent, God’s salvation of man differs from God’s salvation of a beast.
Thus, after all the inquiries and scrutinies, we find that the only need in man’s wishes, which does not exist in the whole of the animate species, is the awakening towards Godly Dvekut (adhesion). Only the human species is ready for it, and none other.
It follows that the whole issue of presence in the human species is in that preparation imprinted in him to crave His work, and in that, he is superior to the beast. And many have already said that even the intelligence in craftsmanship and in political conducts is present, with great wisdom, in many elements in the animal world.
Accordingly, we can also understand the matter of the absence that precedes the existence of man as the negation of the desire for God’s proximity, since one is in the animate degree. Now we understand the words of the phrase that said, “Begins with denunciation, and ends with praise.” This means that we must remember and research the absence that precedes our existence in a positive manner, as this is the denunciation that precedes the praise, and from it we will understand the praise more profoundly, as it is written, “Begins with denunciation, and ends with praise.”
This is also the meaning of our four exiles, exile by exile, which precede the four redemptions, redemption by redemption, up to the fourth redemption, which is the complete perfection that we hope for soon in our days, Amen. Exile refers to “absence that precedes the presence,” which is redemption. And since this absence is what prepares for the HaVaYaH ascribed to it, like the sowing that prepares the reaping, all the letters of redemption are present in exile, except for the Aleph, since this letter indicates the “Aluph (Champion) of the world.” 
This teaches us that the form of the absence is but the negation of the presence. And we know the form of the presence – redemption – from the verse, “and they shall teach no more every man his neighbor …for they shall all know Me, from the least of them unto the greatest of them.” Hence, the form of the previous absence, meaning the form of exile, is only the absence of the knowledge of the Lord. This is the absence of the Aleph, which is missing in the Gola (exile), and present in the Geula(redemption) – the Dvekut with the “Champion of the world.” This is precisely the redemption of our souls, no more and no less, as we have said that all the letters of Geula are present in Gola, but the Aleph, which is the Champion of the world.
To understand this weighty issue, that the absence in itself is what prepares the presence ascribed to it, we should learn from the conducts of this corporeal world. We see that in the concept of freedom, which is a sublime concept, only a chosen few perceive it, and even they require appropriate preparations. But the majority of the people are utterly incapable of perceiving it. Conversely, with regards to the concept of enslavement, the small and the great are equal: even the least among the people will not tolerate it.
(We saw that in Poland, they lost their kingdom only because the majority of them did not properly understand the merit of freedom and did not preserve it. Hence, they fell under the burden of subjugation under the Russian government for a hundred years. During that time, they all suffered under the burden of subjugation and desperately sought freedom from least to great. And although they did not yet assume the taste of freedom as it truly is, each of them imagined it as they wanted, but in the absence of freedom, which is subjugation, it was thoroughly engraved in their hearts to cherish freedom.
For this reason, when they were liberated from the burden of subjugation, many of them were bewildered, not knowing what they have gained by this freedom. Some of them even regretted it and said that their government was burdening them with even more taxes than the foreign government, and wished for their return. This was so because the force of absence did not sufficiently affect them.)
Now we can understand the dispute between Rav and Shmuel. Rav interprets the phrase as beginning with denunciation, so that through it the salvation will be thoroughly appreciated. Hence, he says to begin from the time of Terah. And he does not say what Shmuel does, since in Egypt, His love and work was already planted in a few within the nation. Also, the added difficulty of enslavement in Egypt is not a deficiency in itself in the life of the nation called “Adam.”
And Shmuel interprets the phrase, saying that because the absence prepares the presence, it is considered a part of His salvation, and should be met with gratitude, as well. Hence, we should not begin with, “in the beginning, our fathers were idol worshipers,” since that time is not even regarded as “absence that precedes the presence.” This is because they are completely devoid of the human type of presence, since they were completely removed from His love, like the neuter, which is devoid of love.
Hence, we begin with the enslavement in Egypt, when the sparks of His love were burning in their hearts, to an extent, but due to impatience and hard work, it was being quenched every day. This is considered “absence that precedes the presence,” and this is why he says to begin with “we were slaves.”
And also, it is because the concept of the freedom of the nation in the knowledge of God is a very high concept, which only a chosen few understand, and even then it requires appropriate preparations, but the majority of the people have not attained that. Conversely, perceiving the hardships of enslavement is clear to all, as the Even Ezra wrote in the beginning of Parashat Mishpatim, “Nothing is harder for man than to be in the authority of another man like him.”