Sheldon: It's a bust of Sir Isaac Newton. Penny: Oh sure, sure. Very Christmasy. Sheldon: Well, excuse me, it's much more Christmasy than anything you put on the tree. Leonard: Here we go... Sheldon: December 25th, 1642. Julian calendar. Sir Issac Newton is born. Jesus, however, was actually born in the summer. His birthday was moved to coincide with the traditional pagan holiday that celebrates the winter solstice with lit fires and slaughtered guts, which frankly sounds like more fun than twelve hours of Church with my mother, followed by fruit cake.