I won't talk a lot about Ibn Sina, I would just let him tell you about himself:
"I devoted myself to studying the texts – the original and commentaries – in the natural sciences and metaphysics, and the gates of knowledge began opening for me. Next I sought to know medicine, and so I read the books written on it. Medicine is not one of the difficult sciences, and therefore I excelled in it in a very short time, to the point that distinguished physicians began to read the science of medicine under me. I cared for the sick and there opened to me some of the doors of medical treatment that are indescribable and can be learned only from practice. In addition I devoted myself to jurisprudence and used to engage in legal disputations, at that time being sixteen years old. Then, for the next year and a half, I dedicated myself to learning and reading; I returned to reading logic and all the parts of philosophy. During this time I didn’t sleep completely through a single night nor devote myself to anything else by day.” “At night I would return home, set out a lamp before me, and devote myself to reading and writing. Whenever sleep overcame me or I became conscious of weakening, I would turn aside to drink a cup of wine, so that my strength would return to me. Then I would return to reading. And whenever sleep seized me I would see those very problems in my dream; and many questions became clear to me in my sleep. I continued in this until all of the sciences were deeply rooted within me and I understood them as far as humanly possible. Everything which I knew at that time is just as I know it now; I have not added anything to it to this day. Thus I mastered the logical, natural, and mathematical sciences, and I had now reached the science of metaphysics. I read the Metaphysics of “Aristotle”, but I could not comprehend its contents and its author’s object remained obscure to me, even when I had gone back and read it forty times and had got to the point where I had memorized it. In spite of this I couldn’t understand it nor its object, and I despaired of myself and said, “This is a book which there is no way of understanding.” But one day in the afternoon when I was at the booksellers’ quarter a salesman approached with a book in his hand which he was calling out for sale. He offered it to me, but I refused it with disgust, believing that there was no merit in this science. But he said to me, “Buy it, because its owner needs the money and so it is cheap. I’ll sell it to you for three dirham's.”So I bought it and, lo and behold, it was Abu Nasr al-Farabi’s book on the objects of the Metaphysics. I returned home and was quick to read it, and in no time the objects of that book became clear to me because I had to the point of having memorized it by heart. I rejoiced at this and the next day gave much in alms to the poor in gratitude to God, who is exalted.” Avicenna.