I have no sympathy with the singular combination of intellectual arrogance and intellectual timidity so often presented by this particular school of thought. I like it no better than I like the attitude of those who declare that, since reason is bankrupt, authority should take over its liabilities, however small be the prospect of discharging them in full. My point of view is utterly different. And if I urge that the criticism of common knowledge brings us ultimately to Theism, this involves no intolerable paradox, nor indeed anything very new or strange. Descartes, for example, thought that all knowledge was based on clear and distinct ideas, and that clear and distinct ideas could be trusted because, being due to God, they were guaranteed by His truthfulness. That there is a God possessing every perfection was independently established by an _a priori_ argument into which I need not enter. But the point of interest is that, though Descartes conceived himself to have found a refuge from scepticism in the famous “I think, therefore I am,” he could only get from this narrow assurance to general knowledge by the use of “clear and distinct ideas” certified by divine veracity. If, therefore, belief in one’s self was the first of truths, belief in God was the second; and on this second truth all subordinate beliefs, mathematical, physical, and metaphysical, were, in his opinion, ultimately founded. In one sense, and from one point of view, this is no doubt an exact inversion of the argument developed in these lectures. Descartes rests the belief in science on a belief in God. I rest the belief in God on a belief in science. Nevertheless, beneath this contrast there is deep-lying agreement. Both views reject the notion that we possess in the general body of common-sense assumptions and scientific truths a creed self-sufficing and independent, to which we may add at our pleasure Theism in such doses as suit our intellectual palate. Both views, therefore, are profoundly divided, not merely from all that calls itself agnostic, but from much that calls itself religious.