The term monad (from Ancient Greek μονάς (monas) 'unity', and μόνος (monos) 'alone') is used in some cosmic philosophy and cosmogony to refer to a most basic or original substance. As originally conceived by the Pythagoreans, the Monad is the Supreme Being, divinity or the totality of all things. According to some philosophers of the early modern period, most notably Gottfried Wilhelm Leibniz, there are infinite monads, which are the basic and immaterial elementary particles, or simplest units, that make up the universe. Source: Wikipedia (en)