When my son turned five, he noticed that his friends had all begun to lose their teeth. Adults rushed to reassure him that when his own teeth inevitably fell out, an intruder would come in the night and offer him cash for them. He responded, reasonably, with panic.

For weeks, he’d break into tears, exclaiming, “I won’t lose my teeth! I love my teeth!” During dinner, he’d lean over and ask me casually, “Are Papa’s teeth going to fall out? Are Pop Pop’s? Are yours?” then whisper ferociously, “Mine aren’t!” At some point, he developed a routine of scuttling around like Charlie Chaplin directed by Tim Burton, smacking his gums and muttering eerily, “My teeth! My teeth! I’ve lost my teeth!”

Odd as his behavior may have appeared, I understood that he was learning something simple and true about life: how it can be taken from us subtly, piece by piece, and how it always ends in death. The loss of a few baby teeth seems like nothing until we consider, as a preschooler of average intelligence does intuitively, that it precedes the loss of everything and everyone we love. My son’s anxiety was obsessive, but it was not pathological or a hindrance to his development. In fact, it was his development.