The Fields Medal is the highest honor a mathematician can receive. Paul Erdös never won it. But a number of the people he helped did, and that leads us to what Erdös is best known for: the “Erdös number.” No, it was not a theorem or a mathematical tool. It was simply a measure of how close you were to working with Paul Erdös.

There are so, so many of these men freckled throughout history. Paul Erdős, a renown mathematician characterized by his eclectic genius and all-consuming obsession with math, didn’t butter his own toast until he was an adult. There are several stories recounting how he often offloaded domestic or non-math related tasks to the women in his life

Einstein invented everything he was ever going to invent by the age of 25. The rest of his life was spent in a futile chase to find a force he couldn’t find called the Fifth Force—the unifying force.