Closely connected with the materialism of the Stoics, and equally adverse to the principles of Plato and Aristotle, was their fatalism. In opposition to this, Plotinus proceeds to develop the spiritualistic doctrine of free-will.[438] In the previous discussion, we had to notice how closely his arguments resemble those employed by more modern controversialists. We have here to point out no less wide a difference between the two. Instead of presenting free-will as a fact of consciousness which is itself irreconcilable with the dependence of mental on material changes, our philosopher, conversely, infers that the soul must be free both from the conditions of mechanical causation and from the general interdependence of natural forces, because it is an individual substance.[439] In truth, the phenomena of volition were handled by the ancient philosophers with a vagueness and a feebleness offering the most singular contrast to their powerful and discriminating grasp of other psychological problems. Of necessarianism, in the modern sense, they had no idea. Aristotle failed to see that, quite apart from external restraints, our choice may conceivably be determined with the utmost rigour by an internal motive; nor could he understand that the circumstances which make a man responsible for his actions do not amount to a release of his conduct from the law of universal causation. In this respect, Plato saw somewhat deeper than his disciple, but created fresh confusion by identifying freedom with the supremacy of reason over irrational desire.[440] Plotinus generally adopts the Platonist point of view. According to this, the soul is free when she is extricated from the bonds of matter, and determined solely by the conditions of her spiritual existence. Thus virtue is not so much free as identical with freedom; while, contrariwise, vice means enslavement to the affections of the body, and therefore comes under the domain of material causation.[441] Yet, again, in criticising the fatalistic theories which represent human actions as entirely predetermined by divine providence, he protests against the ascription of so much that is evil to so good a source, and insists that at least the bad actions of men are due to their own free choice.[442]