You think the answer is obvious because you've read the Haggadah before. But, what if I told you that 'Pesach' existed before Makkas Bechoros (even if ever so slightly)? And what about that Rashi in Bo which you never noticed? Never noticed it, right? Of course not--it's the one you that have never noticed. While we are here, what does the word 'Pesach' actually mean?
