The power of speech and the power of free choice are two abilities that are unique to humans. In Mitzrayim, we suffered from a failure to use the power of speech properly. On the night of Pesach, we use our power of speech and free choice in the proper way, choosing to speak about miracles. Yetzias Mitzrayim is part of a broader picture, bringing us back to the way Adam was before the chet (sin). When we tell the story over to our children, we use the power of speech to affirm what man is supposed to be when we came out of Mitzrayim.