Phrenology was a science that portioned off different parts of the brain and associated each with a personality trait. By observing the shape of your head, practitioners believed themselves able to determine your personality based on which areas of your brain were bigger.
Physiognomy, on the other hand, was the study of assessing someone’s personality based on their facial features. It has largely been debunked, but has managed to cling desperately to modern relevance due to findings that people judge each other based on facial features in relatively consistent ways regardless of the accuracy of said judgments.
Humorism was a widespread medical theory for centuries, showing up in various mutations since the Ancient Greeks. It revolved around balancing the four natural “humors” in the human body: blood, phlegm, black bile and yellow bile. They had a somewhat elemental opposition to one another; blood was hot and wet, phlegm was cold and wet, yellow bile was hot and dry, and black bile was cold and dry. All ailments were believed to be caused by either an excess or dearth of these substance, and treatment revolved around rebalancing their amounts. In other words, old-school doctors had a habit of draining blood out of their patients.
Numerology has something to do with numbers symbolizing divine things. I tried to learn more about it but I became violently bored.
It was formerly believed that anything flammable achieved this status by containing something called Phlogiston.