Ibn Sina: The science of medicine

A physician attends to a sick man at his bedside, taking his pulse and looking over him with concern.
Detail from an illustration in a Persian medical text copied in 19th century India (LoC 2017481041).

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:

Two lines of Arabic text: a red section heading followed by black body text in nasta'liq script.
Detail from an 19th-century copy of Ibn Sina's al-Qanun fi al-tibb. (LoC 2021667335)