"Oration on the Dignity of Man" was written by Pico della Mirandola who was a Renaissance philosopher. In it Pico addresses key ideas pertaining to humankind's mode of existence including the insatiable quest for knowledge and the ability to climb to higher plains of being by exercising intellectual prowess. In correlation with these two, in the oration Pico posited what is called Pico's 900 Theses, which enumerate the ways to discover knowledge and physics and in which he combined wisdom from past great philosophical teachings such as Platonic, Aristotelian and Kabbalic teachings. In addition, he spoke of the "mystical" quality of humankind's quest for vocation and the ability to achieve. Further, he contradicted the clergy's opinion by advocating the pursuit of "liberal arts," such as mathematics and philosophy (as opposed to purely clerical religious study), and by propounding the position that by pursuing the rational, humankind makes itself like the angels, creatures of Heaven instead of creatures of Earth. This oration, written and first delivered in 1486, was controversial because of the highly religious milieu of the Renaissance era.