"He who in reasoning cites authority is making use of his memory rather than of his intellect."
--- "Thoughts on Art and Life" by Leonardo Da Vinci
"All our knowledge is the offspring of our perceptions."
"There is nothing which deceives us as much as our own judgement."
"The greatest deception which men incur proceeds from their opinions."
[Sidenote: Against Doctors]
94.
Men are chosen to be physicians in order to minister to diseases of which they are ignorant.
95.
Every man wishes to amass money in order to give it to the physicians who are the destroyers of life; they ought therefore to be rich.
96.
Take pains to preserve thy health; and thou wilt all the more easily do this if thou avoidest physicians, because their drugs are a kind of alchemy, and there are as many books on this subject as there are on medicine.
--- "Thoughts on Art and Life" by Leonardo Da Vinci