All through antiquity and the Middle Ages, right up until modern times, chickens only laid eggs for part of the year – mainly in the spring, when there was plenty of daylight but it wasn’t too hot out. That’s why we have Easter eggs and the egg on the Seder plate – to celebrate the return of eggs in the spring. A lot of traditional egg recipes call for other foods that are in season in the spring, like chives or asparagus.