Good and Bad Luck of Days and Their Avicennian Explanation by Nasir al-Din al-Tusi

have been traditionally paid attention. Many people believe that celestial circumstances play a decisive role in their life events. Scientifically speaking, this is an irrefutable issue, such as the effect of lunar eclipse and solar eclipse on natural phenomena. Unscientifically, however, this has typically manifested as superstitions in people’s lives. Whether celestial circumstances can, in addition to their natural effects, determine value concepts such as good and bad luck of days has even involved philosophers, one of whom is Nasir al-Din al-Tusi. The main question of this research is that which type of philosophical explanation Nasir al-Din al-Tusi has proposed for good and bad luck of days and what his respective Avicennian fundamentals are. This research investigated the good and bad luck of days and their ascription to celestial circumstances from philosophers’ viewpoint, particularly Nasir al-Din al-Tusi. He believed that given the capability of human spirit to affect and be affected by objects, celestial interactions and motions as well as the shape and arrangement of stars and celestial bodies can cause good and bad luck in human life and influence objects on the Earth.