Thomas Willis
Those who are born of parents broken with old age, or of such as are not yet ripe or are too young, or of drunkards, soft or effeminate men, want a great and liberal ingenuity or wit.
Sometimes a great wound or concussion of the head, especially which happens by falling headlong from an high place, brings a prejudice and weakness to the animal faculty, dulling the understanding.
Persons that are stupid we may imagine, sometimes an excess of some manifest quality in the Brain... for which reason Children and aged Persons are often wont to be affected with a Dulness of the Senses: sometimes a texture too gross and earthy, so that the Spirits cannot easily irradiate it, or make Tracts for themselves.
Melancholy... is a complicated Distemper of the Brain and Heart: For as Melancholick people talk idly, it proceeds from the vice or fault of the Brain, and the inordination of the Animal Spirits dwelling in it; but as they become very sad and fearful, this is deservedly attributed to the Passion of the Heart.
I beg my Children to be just and virtuous, never to disgrace my name or theirs, and then they are out of fortune's power.
Diabetes is caused by melancholy.
As to what respects the cure of this Disease, Stupidity, whether innate or acquir'd (if it not be a plain senselessness, and doltishness incapable of all Erudition) though it be not usuall be cured, yet it is want to be amended.