  For Henry (as for Avicenna) every res possesses its own “certitude” (certitudo) that makes it what it is. Certitudo here means stability, consistency, and ontological self-identity: a triangle is a triangle and nothing else, white is white and nothing else. Certitudo thus expresses the objective content by which every thing is identical to itself and is distinguished from other things; in other words, certitudo expresses the essence or quidditas of a thing (“unaquaeque res habet certitudinem propriam quae est eius quidditas” — “every thing possesses its own certitude, which is its essence”). This content can be considered in itself, as independent from its physical or mental existence. In an absolute sense, every essence possesses a double indifference: with regard to actual existence or non-existence (essence in itself is simply possible), and with regard to universality and particularity. These last two aspects are really conjoined. Essence is particular in that it receives its subsistence in a given suppositum (concrete individual entity) from something-other-than-itself, while it is universal in that it is abstracted by the intellect from these singular supposita, in which it exists as one in many, in order to become predicable by many.