The most remarkable feature in these later dialogues is the disappearance, or even in some cases the apparently hostile criticism, of the doctrine of Ideas, and consequently of Reminiscence as the source of knowledge, and even, apparently, of Personal {155} Immortality, so far as the doctrine of Reminiscence was imagined to guarantee it. This, however, is perhaps to push the change of view too far. We may say that Plato in these dialogues is rather the psychologist than the metaphysician; he is attempting a revised analysis of mental processes. From this point of view it was quite intelligible that he should discover difficulties in his former theory of our mental relation to the external reality, without therefore seeing reason to doubt the existence of that reality. The position is somewhat similar to that of a modern philosopher who attempts to think out the psychological problem of Human Will in relation to Almighty and Over-ruling Providence. One may very clearly see the psychological difficulties, without ceasing to believe either in the one or the other as facts. Throughout Plato's philosophy, amidst every variation of expression, we may take these three as practically fixed points of belief or of faith, or at least of hope; _first_, that Mind is eternally master of the universe; _second_, that Man in realising what is most truly himself is working in harmony with the Eternal Mind, and is in this way a master of nature, reason governing experience and not being a product of experience; and _thirdly_ (as Socrates said before his judges), that at death we go to powers who are wise and good, and to men departed who in their day shared in the divine wisdom and goodness,--that, in short, there is something remaining for the dead, and better for those that have done good than for those that have done evil. The first of the 'psychological dialogues,' as we have called them, is the _Philebus_. The question here is of the _summum bonum_ or chief good. What is it? Is it pleasure? Is it wisdom? Or is it both? In the process of answering these questions Plato lays down rules for true definition, and establishes classifications which had an immense influence on his successor Aristotle, but which need not be further referred to here. The general gist of the argument is as follows. Pleasure could not be regarded as a sufficient or perfect good if it was entirely emptied of the purely intellectual elements of anticipation and consciousness and memory. This would be no better than the pleasure of an oyster. On the other hand, a purely intellectual existence can hardly be regarded as perfect and sufficient either. The perfect life must be a union of both.