The knowledge of anything, since all things have causes, is not acquired or complete unless it is known by its causes.
AvicennaMedicine deals with the states of health and disease in the human body. It is a truism of philosophy that a complete knowledge of a thing can only be obtained by elucidating its causes and antecedents, provided, of course, such causes exist. In medicine it is, therefore, necessary that causes of both health and disease should be determined.
AvicennaThe world is divided into men who have wit and no religion and men who have religion and no wit.
Avicenna