The Foundation Stone Haggadah: Karpas 5
In Kabbalah, Karpas represents Din. (See Shelah HaKodesh, Masechet Pesachim, Chelek Matzah Shemura #149 for a more detailed explanation.) The salt represents harshness. Karpas = Samach Perach. The act of dipping represents the softening of Din.
*See also the Ishbitzer who explains the difference between fruit and vegetables. And Rav Kook who uses Karpas to explain how the same act can be both in sorrow and in freedom, also represented by the breaking of the middle Matzah.
It seems to me that the real question about dipping will come only after the second dipping, which is when we really are calling attention to it; the child senses a pattern. (See Maharal.) Karpas is the first step of a process that will only be completed later. This is also true about the Beracha on the Karpas that is on the Marror we will only eat later. Karpas is a symbol of the beginning of something that will end later. It is a reminder that what happened in Mitzrayim will only be completed with the final redemption.
The Chidah, Simchat Haregel, quotes Rabbeinu Manoach who, in his commentary to the Rambam, says that the Karpas is a reminder of the Ketonet Passim – The Coat of Many Colors of Yosef which led to our going down to Egypt. We can apply this in a very powerful way; The brothers were functioning on their own free will, and yet it led to what God would say would happen. Yosef, in his responses to his brothers, both when he revealed his identity and after Yaakov died, recognizes how the the Hand of Hashem was guiding everything; even his dreams. God used Josef’s strengths and weaknesses, as He did with the brothers to control their destiny. Pesach is a time in which Bechira is an issue; Why were the Egyptians punished? Why did Hashem harden Pharaoh’s heart? This issue of control through us is fundamental to understanding freedom. Freedom is Bechira, both in the choosing, and in its power; choices matter. We are celebrating tonight our freedom and our free will. We are also recognizing that Hashem’s control does not contradict our choices.