Medicine 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.
AvicennaLeeches should be kept a day before applying them. They should be squeezed to make them eject the contents of their stomachs.
Avicenna