In the Porphyrian period, he rejected the idea of intelligible matter.[475] Forced to fashion entirely new arguments, he seizes as tool the Aristotelian distinction between potentiality and actuality, or energy as dynamic accomplishment.[476] But no logical device can help a man to pull himself up by his boot-straps. If by Being you mean existence, then its opposite must be negative, and to speak of real non-being, as something that shares being, is an evasion. To say that matter remains non-being, while having the possibility of future Being, which however can never be actualized, is mere juggling with words. Even if matter is no more than a weak, confused image, it is not non-being. If it is a positive lie, it is not non-being. To talk of a higher degree of Non-being, that is real non-being, is simply to confuse the actuality intended with the thought of non-being, which of course is a thought as actually existing as any other. Moreover if matter is imperishable, it cannot be non-being; and if it possesses Being potentially, it certainly is not non-existence. The Aristotelian potentiality could help to create this evasion, but did not remove its real nature; it merely supplied Plotinos with an intellectual device to characterize something that would not be actually existing as still having the possibility of existence; but this is not non-existence. In another writing[477] of this period Plotinos continues his evasions about the origin and nature of matter. First, he grants that it is something that is not original, being later than many earthly, and all intelligible objects; although, if he had returned to the conception of intelligible matter, he would have been at liberty to assert the originality of the latter. Then he holds that Being is common to both form and matter, as to quality, but not as to quantity. Last, he closes the paragraph by saying that perhaps form and matter do not come from the same origin, as there is a difference between them. In Plotinos's third, or Eustochian period, the same evasions occur. For instance[478] he limits Being to goodness. Then he acknowledges the existence of evil things, and derives their evil quality from a primary evil, the "image of essence," the Being of evil. That he is conscious of having strained a point is evident from the fact that he adds the clause, "if there can be a Being of evil." Likewise,[479] while discussing evil, which is generally recognized because in our daily lives there is positive pain, and sensations of pain, he defines evil as lack of qualities. To say that evil is not such as to form, but as to nature is opposite to form is nonsense, inasmuch as life is full of positive evils, as Numenius brought out in 16, and Plotinos acknowledged even in spite of his polemic against the Gnostics.