Pesachim 116 - Second cup of wine
After the first cup wine at the Seder, they immediately pour the second one. Now the curiosity of his son is aroused, and he is supposed to ask, "What is so different about this night that you are drinking a second cup of wine, without having even eaten?" If the son is not observant enough to notice, his wife asks him the same question. And that is the question that he was waiting for, for now he can plunge into the Haggadah, which providers the answer: "It is because we were slaves once, and now we are free to do as we please and to server our Creator!"
Thus, the well-known " Four Questions of the Seder " are only a formula for those whose curiosity is not naturally aroused in the course of daily life. However, there is also another interpretation, according to which the proper way is to ask the Four Questions exactly as they are spelled out in the Hagaddah.
As Rabban Gamliel taught, every person has to imagine that he personally was a slave and then went out of Egypt and became a free man, and the Hagaddah should be read with that understanding in mind - and that is why one is supposed to praise and extoll God for all the miracles and to say the collection of Psalms known as Hallel (praise).
Art: A Ride for Freedom - The Fugitive Slaves by Eastman Johnson