Among many writings of the brilliant scholar, philosopher and writer Avicenna (from his Arabic name Abu Ali al-Hussayn b. Abd Allah Ibn Sina, born in 980 in Afsana, close to Bohara, and deceased in 1037 in Hamadan), the sixth book of his big work “Ash-shifaa“ (The Book of Healing), treating the subject of psychology , is highly significant by his importance. During the Greek antiquity as well as in the Middle Age, in Asia and in Europe, psychology had probably been, within the wide frame of philosophy and natural sciences, the most important scientific branch, for the questions it rises extend to all the phenomenon of life but mostly to the problems of sensible and intellectual knowledge, and also the problems regarding the union of the body and soul, from here, psychology enters the field of ancient natural sciences.