Spinoza's Substance

Spinoza’s concept of Substance refers to the fundamental reality that underlies and unites everything in existence. He believed there is one ultimate Substance—often identified with God or Nature—that is infinite, self-caused, and the source of all that exists. Everything we observe—objects, thoughts, forces—are modes or expressions of this single Substance. This means nothing exists outside of it, and its essence is absolute, necessary, and indivisible. In simple terms, Substance is the single, universal "thing" that holds everything together and from which everything arises.