This Element examines the contemporary literature on essence in connection with the traditional question whether essence lies within or without our world. Section 1 understands this question in terms of a certain distinction, the distinction between active and latent facts. Section 2 steps back to investigate the connections between essence and other philosophical concepts. Section 3 brings the results of this investigation to bear on the traditional question, sketching an argument from the premise that essentialist facts are explained by the origins of things to the conclusion that such facts are active.