11. I have said that Plato dwells principally on ideas in their higher function as instrumental in the construction of science, and that he seems to insist with less emphasis on the necessity with which they are present in all, even in our humblest cognitions. I have also said that the importance of ideas, and the value of the theory which expounds them, are much more conspicuous when we look at them in the latter, than when we look at them in the former character. When we regard them as the light of all thought and all knowledge, the theory is admirable (as I hope to show you); when we regard them merely as the light of science, and as the property merely of scientific men, the theory is shorn of its significance. The following remark may perhaps help to clear up or remove the ambiguity which Plato has himself thrown around the theory. Every human being in the simplest act of knowledge makes use of ideas; ideas are present to his mind; but he is not cognisant of their nature and character; he is not aware even of their existence. They are in possession of him, rather than he of them; he is unconscious of their necessary and unfailing presence. To make him conscious of this presence, to make him aware of the necessity and the nature of ideas, a special and difficult science is required, the science of Dialectic. Now, in broaching his theory of ideas, I conceive that what Plato means to inculcate is not that it is difficult for the mind to get hold of ideas, or that any science is required to put us in possession
