A man is crazy who writes a secret in any other way than one which will conceal it from the vulgar.

Cease to be ruled by dogmas and authorities; look at the world!

Mathematics is the gate and key to science.

Argument is conclusive, but it does not remove doubt, so that the mind may rest in the sure knowledge of the truth, unless it finds it by the method of experiment.

Reasoning draws a conclusion, but does not make the conclusion certain, unless the mind discovers it by the path of experience.

To ask the proper question is half of knowing.

As regards authority I so proceed. Boetius says in the second prologue to his Arithmetic, 'If an inquirer lacks the four parts of mathematics, he has very little ability to discover truth.' And again, 'Without this theory no one can have a correct insight into truth.' And he says also, 'I warn the man who spurns these paths of knowledge that he cannot philosophize correctly.' And Again, 'It is clear that whosoever passes these by, has lost the knowledge of all learning.'