Except our own thoughts, there is nothing absolutely in our... - René Descartes

"There is nothing more ancient than the truth."

"To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them."

"But in my opinion, all things in nature occur mathematically."

"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things."

"I think; therefore I am."