Coincidences can feel like magic. When we realize that a co-worker shares our birthday or run into a college roommate while on vacation, it can give us a surge of delight. Today, we revisit a favorite episode about these moments of serendipity. Mathematician Joseph Mazur explains why coincidences aren't as unlikely as we think they are, and psychologist Nicholas Epley tells us why we can't help but find meaning in them anyway.