It follows that each of the lower monads is so far imperfect that it is never at any one time all that it has the possibility of being; the eternal essence of humanity, for example, the truth of humanity, its ideal, is realised not in any one individual, but only in the species as a whole,[582] and this is true of the perfection of every other species. But Bruno's optimism surmounts this difficulty. The evil, the imperfection, is so only to the individual, and in that particular phase of its life. Each thing has a double tendency and a double striving--to remain in the state in which it is, and to press beyond that to realise new forms. But each thing has in itself the nature of the whole--is therefore in its inmost nature perfect. It is imperfect only in its explicit nature--on its outward side. The striving after new life is due to the felt conflict, or want of harmony, between what it has in it to become--its inner self--and what it has actually become, the limited form in which it appears. On the one hand evil is necessary for good, for were the imperfections not felt, there would be no striving after perfection; all defect and sin consist merely in privation, in the non-realisation of possible qualities. "It would not be well were evil non-existent, for it makes for the necessity of good, since if evil were removed the desire of good would also cease."[583] In its whole life, however, the soul will realise all good, and therefore is only _per accidens_ imperfect. On the other hand, however mean in itself at any moment, it is a necessary part of the whole, and therefore, relatively to the whole it is good. "If we look to the order of the universe it will appear that every action and effect is good by way of necessity, for even the things which appear the most trifling and sordid are parts of greater and more noble things, as the formless are parts of the formed, the least are necessary elements of the great, the great of the greatest; and as the less cannot subsist without the least, so neither can the greatest without the great. All beings, therefore, of whatsoever nature, are good, if they are rightly considered, not less good than greater things, if we take into account the fact that the goodness of the whole depends on the goodness of its parts."[584]