Avicenna (980 - 1037) was a Persian Islamic philosopher and physician.
The knowledge of anything, since all things have causes, is not acquired or complete unless it is known by its causes.
Avicenna
It is evident that everything which does not exist at first and then exists is determined by something other than itself.
Avicenna
As to the mental essence, we find it in infants devoid of every mental form.
Avicenna
Now it is established in the sciences that no knowledge is acquired save through the study of its causes and beginnings, if it has had causes and beginnings.
Avicenna
That whose existence is necessary must necessarily be one essence.
Avicenna
Therefore in medicine we ought to know the causes of sickness and health.
Avicenna
Medicine considers the human body as to the means by which it is cured and by which it is driven away from health.
Avicenna
