From Rabbi Alan Ullman:

During the plague of darkness, it was so dark (Exodus 10:21-23) that "people could not see one another." But the text notes that "the Israelites enjoyed light in their dwellings". This is the origin of our tradition of lighting candles on holidays, including shabbat, so it is a fitting beginning to the seder.

What does it mean that we are meant to see our brothers' faces in these moments?  


haggadah Section: Introduction
Source: Alisa Ente in torah study