We now come to the third stage in our enquiry. In this section we propose to take up again some of the problems treated in Part I, and to examine them afresh in the light of the conclusions reached on the subject of metaphysics in Part II. It is because the metaphysical basis of such problems is seldom studied or even suspected that the theory of perception often strikes the student as uncommonly dull and abstract: whereas it should be the stepping-stone to all the major issues in philosophy, which are dull only to dull people and a matter of indifference only to indifferent people. In the meantime, however, we have learnt something of the nature of metaphysics and have agreed to define it as an enquiry into the presuppositions upon which men, and groups of men called societies, base their ideas about the world. This means that in our examination of the metaphysical background of modern thought we shall be trying to discern the pattern of modern civilisation.