'Thing' (essence) has priority over 'being', and 'being' is necessarily concomitant with 'thing'.

Another main source is the Persian thinker Ibn Sina (Lat. Avicenna), who discusses the concepts of ‘being’, ‘thing’, and ‘the one’ as the primary conceptions of the intellect in his Metaphysics I.5. He introduces the idea of primary conceptions by drawing a seminal analogy between first principles in the order of judgment and in the order of conception: just as there are first principles in the order of judgment, at which the reduction or analysis of propositional knowledge comes to an end (e.g.