Why, then, ultimately will the notions “square” and “circle” not coalesce so as to form one object of thought for the human mind, while the notions “equilateral” and “triangle” will so coalesce? Because the Essence of God, the Necessary Being, the First Reality, and the Source of all contingent reality, affords no basis for the former as a possible expression or imitation of Itself; in other words, because Being is not expressible by nothingness, and a “square circle” is nothingness: while the Divine Essence does afford a basis for the latter; because Necessary Being is in some intelligible way imitated, expressed, manifested, by whatever has any being to distinguish it from nothingness, and an “equilateral triangle” has such being and is not nothingness. It is hardly necessary to add that when we conceive the Divine Essence, contemplated by the Divine Intellect, as containing in itself the exemplars or prototypes of all possible things, we are not to understand the Divine Essence as the _formal_ exemplar of each, or, _a fortiori_, as a vast collection of such formally distinct exemplars; but only as _virtually_ and _equivalently_ the exemplar of each and all. We are not to conceive that possible essences are seen by the Divine Intellect imaged in the Divine Essence _as in a mirror_, but rather _as in their supreme source and principle_: so that they are faint and far off reflections of It, and, when actualized, become for us the only means we have, in this present state, for reaching any knowledge of the Deity: _videmus nunc per speculum_.(114) 21. DISTINCTION BETWEEN ESSENCE AND EXISTENCE IN ACTUALLY EXISTING CONTINGENT OR CREATED BEINGS.—Passing now from the consideration of possible essences as such, to the consideration of actually existing essences, we have to examine a question which has given rise to a great deal of controversy, partly on account of its inherent difficulty, and partly because of a multitude of ambiguities arising from confusion of thought: What is the nature of the distinction between essence and existence in the actually existing things of our experience?