It is a more qualitative word connected to simple. It is a property, condition, or quality which things can be judged to have. It usually relates to the burden which a thing puts on someone trying to explain or understand it. Something which is easy to understand or explain is simple, in contrast to something complicated. In some uses, simplicity can be used to imply beauty, purity or clarity. Simplicity may also be used in a negative connotation to denote a deficit or insufficiency of nuance or complexity of a thing, relative to what is supposed to be required.
The concept of simplicity has been related to truth in the field of epistemology. According to Occam's razor, all other things being equal, the simplest theory is the most likely to be true. In the context of human lifestyle, simplicity can denote freedom from hardship, effort or confusion. Specifically, it can refer to a simple living lifestyle.
Simplicity is a theme in the Christian religion. According to St. Thomas Aquinas, God is infinitely simple. The Roman Catholic and Anglican religious orders of Franciscans also strive after simplicity. Members of the Religious Society of Friends (Quakers) practice the Testimony of Simplicity, which is the simplifying of one's life in order to focus on things that are most important and disregard or avoid things that are least important.