“Growing old was once something experienced on an individual basis: not at a set age for everyone and not according to a single set of rules. However, in the second half of the 19th century, a more monolithic idea of “the aged” began to take form, shaped in great part by a medical theory that has long since been debunked.
During this period, doctors believed that old age occurred when the body ran out of “vital energy” — which was no mere metaphor. The stuff was thought to be tangible, literally present in the body and its fluids. Everyone had a finite reservoir of vital energy that gradually became depleted over a lifetime. When you began to run low on vitality, you were old; death followed when the tank was empty.”
Why do people get old? History offers up some very weird theories. The Washington Post. December 12, 2017