This is a presentation of the Middle Ages seen through philosophy, different religions of the time, the writings of the Saints, vision scientists at that time ... and so on. In short here RĂ©mi Brague made an interesting tour of the question. Erudition this man is impressive and it is there that is hard to follow. You have to go slowly, step by step and have time to read ahead with the necessary attention. So this is not an easy reading book, for the use of anybody.