The absence of good (), also known as the privation theory of evil, is a theological and philosophical doctrine that evil, unlike good, is insubstantial, so that thinking of it as an entity is misleading. Instead, evil is rather the absence, or lack ("privation"), of good. This also means that everything that exists is good, insofar as it exists; and is also sometimes stated as that evil ought to be regarded as nothing, or as something non-existent. It is often associated with a version of the problem of evil: if some things in the world were to be admitted to be evil, this could be taken to reflect badly on the creator of the world, who would then be difficult to admit to be completely good. The merit of the doctrine in serving as a response to this version of the problem of evil is disputed. History Ancient Greek and Hellenistic philosophy The doctrine is sometimes said to be rooted in Plato. While Plato never directly stated the doctrine, it was developed, based on his remarks on evil, by the Neoplatonist philosopher Plotinus, chiefly in the eighth tractate of his First Ennead. The following quotation from that tractate, in which evil is described as non-being, illustrates this:As these are real beings, and as the first Principle is their superior, evil could not exist in such beings, and still less in Him, who is superior to them; for all these things are good. Evil then must be located in non-being, and must, so to speak, be its form, referring to the things that mingle with it, or have some community with it. This "non-being," however, is not absolute non-being. Its difference from being resembles the difference between being and movement or rest; but only as its image, or something still more distant from reality. Within this non-being are comprised all sense-objects, and all their passive modifications; or, evil may be something still more inferior, like their accident or principle, or one of the things that contribute to its constitution. To gain some conception of evil it may be represented by the contrast between measure and incommensurability; between indetermination and its goal; between lack of form and the creating principle of form; between lack and self-sufficiency; as the perpetual unlimited and changeableness; as passivity, insatiableness, and absolute poverty. Those are not the mere accidents of evil, but its very essence; all of