‘Tesla is rumored to have believed that the numbers three, six, and nine had special powers. Allegedly, he once said, “If you only knew the magnificence of the three, six, and nine, then you would have a key to the universe.”

Historians have not found a definitive source for this quote, but that hasn’t stopped it from taking off and sparking a great deal of speculation among those looking for a cheat code to the cosmos.

The number three has long been recognized as a powerful digit. Sacred trinities—like the Father, Son, and the Holy Ghost in Christianity—appear frequently across various religions. Tesla himself reportedly cited “energy, frequency, and vibration” as the three elements that he believed held the key to understanding the nature of the universe.

The inventor certainly had a well-documented interest in the number three. In Tesla’s life, this interest led to an obsession with the number that some have connected to possible OCD. Tesla would often walk around blocks three times before entering buildings, and would use 18 napkins—a multiple of three—to wash his dishes. He also insisted on staying in hotel rooms with room numbers that were divisible by three, and died in room #3327 of the New Yorker Hotel in 1943….’ (Eden Gordon via Mental Floss)