The same observations apply also to Plotinus and his successors. These philosophers are not lacking in an elaborate science of metaphysics. The care which they devoted to this science leaves no doubt as to their lively interest in scientific completeness and systematic arrangement. For all that their speculative efforts bear the same relation to the practical aim of philosophy as those of the Stoics, who in point of learning and logical elaboration of a system are quite their equals. A real interest in knowledge was no doubt one of the elements which brought Neoplatonism into being; but it was not strong enough to counterbalance another, the practical and religious sentiment. The mind was not sufficiently independent to be able to get on without appealing to intellectual and theological authorities; the scientific procedure was too mixed to lead to a simple study of things as they are. As in the case of the Neopythagoreans, the ultimate ground of the system is a religious want. The divine world is only a portion of human thought projected out of the mind, and incapable of being fully grasped by the understanding. The highest business of philosophy is to reunite man with the divine world external to himself. To attain this end, all the means which science supplies are employed. Philosophy endeavours to explain the steps by which the finite gradually came to be separated from the original infinite being; it seeks to bring about a return by a regular and systematic course; and in this attempt the philosophic spirit of Greece, by no means extinct, proved its powers by a result of its kind unrivalled. In the first instance, no doubt, the problem was so raised as to press philosophy into the service of religion; but, in the long run, it became apparent that, with the premises assumed, a scientific solution of the religious question was impossible. The idea of an original being with which the system started was a reflex of the religious sentiment, and not the result of scientific research, and the doctrine of a mystical union with a transcendental being was a religious postulate, the gratuitous assumption of which betrays an origin in the mind of the thinker. The platform of Neoplatonism is the same, therefore, as that of the other post-Aristotelian systems; and it is hardly necessary in proof of this position to point to the agreement of Neoplatonism in other respects with Stoicism, and especially in ethics. Far as the two systems lie asunder, the one standing at the beginning the other at the end of the post-Aristotelian philosophy, nevertheless both display one and the same attitude of thought; and we pass from one to the other by a continuous series of intermediate links.