To be is to be the value of a variable.

Our statements about the external world face the tribunal of sense experience not individually but only as a corporate body.

No entity without identity.

Emptiness wrongly grasped destroys the slow-witted, like a snake wrongly seized or a spell wrongly cast.

-- Nagarjuna

The course of Heaven is constant: it does not prevail because of Yao, nor does it cease because of Jie.

-- Xunzi

Divide each difficulty into as many parts as possible for a better solution.

-- René Descartes

Do not block the way of inquiry.

-- Charles Sanders Peirce

To the things themselves!

-- Edmund Husserl

A theory which is not refutable by any conceivable event is non-scientific.

-- Karl Popper