The Pesach sacrifice is the only one that took place before there was a mishkan, a sacred place, in which to carry it out. On the night of the last plague, the lamb's blood was painted onto the doorposts. On an explicit level, the blood protected the people from death. On a deeper level, by marking their houses with blood, the people turned their houses into symbolic wombs marked with the blood of birth, thereby marking themselves as ready to be born.
The Torah describes the requirement to cook the Pesach sacrifice whole like this: it must be roasted with "its head on its knees and gut" [Ex 12:9]. The Baal Shem Tov suggests a deeper meaning to this image when he uses the same phrase to explain the sparks of holiness found in every being: "Every spark...has in it a complete body komah sh'leymah of 248 parts and 365 connectors, and when it is within the silent or the growing being, it's in the prison house, for it cannot spread out its hands and its legs or speak, for 'its head [is] on its knees and gut'."
The rabbis already taught that all the "part and connectors" of the human body corresponded to one of the 613 commandments [248+365=613], and the Kabbalah already extended this image to the world as a whole, but the Besh"t extended this symbol one step further to include the individual sparks of the "more-than-human world". To me, the image of the spark, with "its head on its knees and gut," sounds like a fetus curled up inside the womb, ready to be released. Every single thing is full of sparks waiting to be born. How we interact with the sparks is what enables them to unfold into the world.
Even in the times of the Temple, the paschal lamb still was't eaten in the sacred place of the Temple Mount, but rather in the sight of the Temple in the hills around Jerusalem. We could say that this is because the holy sparks are everywhere, not just in the officially holy places. We need to midwife them, to unfold their stature, by treating every object with respect and every being with love. This is the purpose of Torah, according to the Baal Shem Tov.
We might say that that is also the purpose of Passover – to liberate all the sparks, to redeem every being. According to the Besh"t, this is also "the purpose of a Jew's work in Torah and mitsvot." If we can bring that kavanah to our seders, we can birth so much blessing in the world.
R. David Seidenberg