On the Seder plate, there is a designated section for an egg. All the sections have a more obvious role; but the egg’s place is less clear.
The Ishbitzer teaches that the egg is symbolic of the nascent Jewish nation; like an egg requires nurturing and warmth to hatch, so the newly formed nation was, on its way to “hatching” at Mount Sinai, upon receiving the Torah.
The Rema says that this is the very same egg as on 9 Av, and points out that the fast of 9 Av will always be on the same day of the week as the first night of Pesach. But there is more to it than that.
Avraham was told his descendants would be enslaved in Egypt. When they left Egypt, the Torah recounts how וּמוֹשַׁב בְּנֵי יִשְׂרָאֵל אֲשֶׁר יָשְׁבוּ
בְּמִצְרָיִם שְׁלֹשִׁים שָׁנָה וְאַרְבַּע מֵאוֹת שָׁנָה – the settlement of the Jews in Egypt lasted 430 years (12:40). Not commonly cited, is that “only” 86 of the years spent in Egypt were spent in slavery, which Miriam’s birth marked (hence her name, meaning “bitter”). The early departure was forced because the Jews were mired in the depths of decadence, the 49th level of impurity, beyond which they could not be saved. They had to leave early, if they were ever to leave.
But this means that only one fifth of the prophesied 430 years of slavery was spent in actual slavery. This is slightly hinted to when Yosef interpreted the butler’s dream, where he described how he’d squeezed grapes for Paroh. In the dialogue, the word כוס appears four times. Figuratively, Yosef announced that when the cup was squeezed into, he would walk free, and the same with the Jews in Egypt, that when they were “squeezed” into the כוס – 86 – they walked free. That only one fifth of the time was served is one the explanations of the bizarre word וחמושים – also a source that many Jews did not live to escape Egypt, perishing in the darkness.
The deficit in time is 344 – the word כוס multiplied four times, the numerical value of שמד – disaster. On 9 Av, the Torah portion we read berates us and says שָּׁמֵד תִּשָּׁמֵדוּן – we owe for our early, forced departure from egypt. And on the eve of 9 Av, we eat an egg, in memory of the destruction and imperfection of the world.
As the Rema says, this is the very same egg as on 9 Av. We left early, but leaving Egypt was not the perfect redemption, which we still await. We remind ourselves of this with the egg we eat before 9 Av.