Books VIII. and IX. (on Friendship) are almost an interruption of the argument. The subject-matter of them was a favourite topic of ancient writers, and the treatment is smoother and more orderly than elsewhere in the _Ethics_. The argument is clear, and may be left without comment to the readers. These books contain a necessary and attractive complement to the somewhat dry account of Greek morality in the preceding books, and there are in them profound reflections on what may be called the metaphysics of friendship or love.
At the beginning of Book X. we return to the topic of Pleasure, which is now regarded from a different point of view. In Book VII. the antagonists were those who over-emphasised the irrationality or badness of Pleasure: here it is rather those who so exaggerate its value as to confuse or identify it with the good or Happiness. But there is offered us in this section much more than criticism of the errors of others. Answers are given both to the psychological question, “What is Pleasure?” and to the ethical question, “What is its value?” Pleasure, we are told, is the natural concomitant and index of perfect activity, distinguishable but inseparable from it—“the activity of a subject at its best acting upon an object at its best.” It is therefore always and in itself a good, but its value rises and falls with that of the activity with which it is conjoined, and which it intensifies and perfects. Hence it follows that the highest and best pleasures are those which accompany the highest and best activity.
Pleasure is, therefore, a necessary element in the best life, but it is not the whole of it nor the principal ingredient. The value of a life depends upon the nature and worth of the activity which it involves; given the maximum of full free action, the maximum of pleasure necessary follows. But on what sort of life is such activity possible? This leads us back to the question, What is happiness? In what life can man find the fullest satisfaction for his desires? To this question Aristotle gives an answer which cannot but surprise us after what has preceded. True Happiness, great satisfaction, cannot be found by man in any form of “practical” life, no, not in the fullest and freest exercise possible of the “moral virtues,” not in the life of the citizen or of the great soldier or statesman. To seek it there is to court failure and disappointment. It is to be found in the life of the onlooker, the disinterested spectator; or, to put it more distinctly, “in the life of the philosopher, the life of scientific and philosophic contemplation.” The highest and most satisfying form of life possible to man is “the contemplative life”; it is only in a secondary sense and for those incapable of their life, that the practical or moral ideal is the best. It is time that such a life is not distinctively human, but it is the privilege of man to partake in it, and such participation, at however rare intervals and for however short a period, is the highest Happiness which human life can offer. All other activities have value only because and in so far as they render _this_ life possible.