Contrary to Harry Nilsson's 1968 song, 1 is not the loneliest number. That number is actually 7, according to David S. Kessler, who has an unusual neurological condition: He sees numbers as people. To him, 0 through 10 are specific characters he's known his whole life. Each has a gender, an age, a personality and even a haircut.
It wasn't until fourth grade that Kessler realised this was not the norm for everyone. So he mostly kept it under wraps, although after figuring out he was experiencing a form of synesthesia (a process in which a person's senses are blended), Kessler started referring to it as "numesthesia."
In 2014, not long after retiring from the National Zoo after 39 years, he read a blurb in The Post's Reliable Source column about a Jeopardy contestant like him.
That's when he discovered he officially has ordinal linguistic personification, which Oliver Sacks mentioned in his 2007 book, Musicophilia.
Kessler still prefers the term he coined 40 years ago, so that's the name of the play he has written for next month's Capital Fringe Festival in Washington, DC. He's the only actor in Numesthesia, which he describes as the story of his numbers and how he has dealt with them.