2. For the first dipping [at the Seder] (1), which is called "karpas",
many people use parsley. It is preferable to use celery, which also tastes
good when eaten raw. The choicest vegetable to use is a radish (2).
(1) The Sages instituted this dipping of a vegetable in salt water before
the meal begins (that is, before eating the matzah), something that is not
done on other nights of the year, in order to stimulate the children's
curiosity and draw them into asking why this night is different from all
other nights - "Ma Nishtana Halaila HaZeh..." Asking the "Four Questions"
during the seder is not supposed to be a ritual formality; rather, there is
an obligation to do things that will stimulate actual curiosity and
questioning, because answers do not make a difference to people who don't
have questions (See Rambam, Yad, Chometz U'Matzah 7:3).
(2) The species called "karpas" includes both celery and parsley; one of
the reasons this species was originally chosen for this dipping, is because
if we reverse the Hebrew letters of the word "karpas," we get the letter
"Samech," which has a numerical value of sixty, alluding to the sixty
myriad (60 times 10,000) of Jewish males above 20 years old who left Egypt,
and the word "Perech" (lit: "break-apart") which alludes to the
"back-breaking" labor. We dip it in salt water to allude to the fact that
the Jews walked through the split Red Sea in order to escape the Egyptian
army. The salt water also alludes to the tears and sweat of the bondage.
Since this pre-meal dipping was instituted primarily to arouse the
curiosity of the children, one may use any vegetable not included in the
family of bitter herbs, that requires a blessing of "boreh pri ho'adamah,"
and that is used as an appetizer. The potato was introduced in some
countries where there were no other affordable vegetables; those who's
ancestors used a potato for "karpas," continue to do so at present.