Ibn Sina: The science of medicine

In The Canon of Medicine, Ibn Sina writes:
Medicine is the science that teaches us the conditions of the human body, in terms of what is healthy and what is not. The goal is to protect health when it exists and recover it when it is lost.
In Arabic:
إن الطب علم يتعرف منه أحوال بدن الإنسان من جهة ما يصح ويزول عن الصحة، ليحفظ الصحة حاصلة، ويستردها زائلة
Notes
The quote above is from the opening to Ibn Sina's great encyclopedic work on medicine, al-Qanun fi al-tibb. Here it is written in black nasta'liq text, in an 18th-century copy of the Qanun:
