Extraordinary claims require extraordinary evidence.

• 

  Facts do not cease to exist because they are ignored.

• 

  The greatest amount of knowledge, if it has not been worked over by one’s own thinking, is worth much less than a far smaller amount that has been thoroughly thought through.

• 

  A man of genius makes no mistakes. His errors are volitional and are the portals of discovery.

• 

  As to diseases, make a habit of two things: to help, or at least to do no harm.

• 

  Happy is he who has been able to learn the causes of things.

• 

  Ignorance more frequently begets confidence than does knowledge.

All quotes