In philosophy, essence is the attribute (or set of attributes) that make an object or substance what it fundamentally is, and that it has necessarily (in contrast with accidental properties that the object or substance has contingently, and without which the substance could have existed). The notion of essence has acquired many slightly but importantly different shades of meaning throughout the history of philosophy; most of them derive from its use by Aristotle and its evolution within the scholastic tradition. Based on such considerations, essence was a key notion of alchemy (cf. quintessence). Modern philosophy In the modern period, some philosophers—such as George Santayana—have kept the vocabulary of essence but have abolished the distinction between essence and accident. For Santayana, the essence of a being simply is, independent from the question of existence. Essence is what-ness as distinct from that-