The passage's language is somewhat difficult, but it appears to speak of eating or dipping2 some food before the main meal. The Mishna mentions chazeret (lettuce) explicitly, but the truncated phrase "and they brought before him" allows for the possibility that other foods or vegetables were brought as well. No reason is given for the custom, and at first glance it would seem to have nothing to do with Pesach and the story of the Exodus. Why, then, has the custom been incorporated into the Seder?
First Course
In the Mishnaic period it was a common practice in Israel that festive meals began with a series of appetizers. This is attested to in several Tannaitic passages,3 which mention assorted appetizers as being part of "סדר הסעודה". Thus, for example, Tosefta Berakhot 4:8, mentions a series of three "פרפריות" that would be served to guests. As the source speaks of washing hands, it further seems that these were normally dipped in some sort of liquid (as only then would ritual hand-washing be required). Such festive meals likely served as the model for the Seder,4 and thus, in its earliest stages, the "vegetable dipping" of Karpas likely had no religious significance. It was simply the natural opening of the meal, meant to whet the appetite for later courses.5 Lettuce might be mentioned explicitly, since it was a common appetizer.6
Sign for the Children
In Amoraic times, a different understanding of the custom appears. Bavli 114b and 117a imply that the dipping was instituted only so that the children will ask: "כי היכי דליהוי היכירא לתינוקות". Though the Bavli is somewhat ambiguous, many Rishonim, including RashiPesachim 114aAbout R. Shelomo Yitzchaki, RashbamPesachim 114aAbout R. Shemuel b. Meir and the Raavan
