Ibn Sina the philosopher

Paul Mas'ad wrote this book to mark the nine hundredth anniversary of the death of the scholar Ibn Sina (Avicenna), considered one of the most influential philosophers in the Islamic world and Europe. He was also a genius in medicine, as his books and discoveries in this field were studied in European universities, especially his book "The Canon of Medicine," which later became a comprehensive encyclopedia of medical information and knowledge.
Ibn Sina divided the sciences into three categories: the higher, which are metaphysical sciences or first philosophy, whose subject is existence; the lower, whose subject is matter, which is concerned with it and is inseparable from it, and is known as physics; and the middle, which is a combination of the higher and lower sciences; that is, it relates to matter on the one hand and is abstract from it on the other, and is known as mathematics.
As for logic, Ibn Sina considered it the instrument that protects the mind from error in what we imagine and leads to true belief by providing its reasons and establishing its paths. It is like a scale to which we can refer when right is confused with wrong, or truth with falsehood. In his logic, he followed the eight books of Aristotle.