Materialism holds that the only things that exist are matter and energy, that all things are composed of material, that all actions require energy, and that all phenomena (including consciousness) are the result of material interactions.
Life is a characteristic which distinguishes objects that have self-sustaining biological processes from those that do not—either because such functions have ceased (death), or else because they lack such functions and are classified as "inanimate".
In mathematics, existence is asserted by a quantifier, the existential quantifier, one of two quantifiers (the other being the universal quantifier). The properties of the existential quantifier are established by axioms.
The word "existence" comes from the Latin word exsistere meaning "to appear", "to arise", "to become", or "to be", but literally, it means "to stand out" (ex- being the Latin prefix for "out" added to the causative of the verb stare, meaning "to stand").
In the Western tradition of philosophy, the earliest known comprehensive treatments of the subject are from Plato's Phaedo, Republic, and Statesman and Aristotle's Metaphysics, though earlier fragmentary writing exists. Aristotle developed a comprehensive theory of being, according to which only individual things, called substances, fully have to be, but other things such as relations, quantity, time, and place (called the categories) have a derivative kind of being, dependent on individual things. In Aristotle's Metaphysics, there are four causes of existence or change in nature: the material cause, the formal cause, the efficient cause and the final cause.