What is experience and what is Reason, Mind? What is the scope of experience and what are its limits? How far is it a sure ground of belief and a safe guide of conduct? Can we trust it in science and in behavior? Or is it a quagmire as soon as we pass beyond a few low material interests? Is it so shaky, shifting, and shallow that instead of affording sure footing, safe paths to fertile fields, it misleads, betrays, and engulfs? Is a Reason outside experience and above it needed to supply assured principles to science and conduct? In one sense, these questions suggest technical problems of abstruse philosophy; in another sense, they contain the deepest possible questionings regarding the career of man. They concern the criteria he is to employ in forming his beliefs; the principles _by_ which he is to direct his life and the ends _to_ which he is to direct it. Must man transcend experience by some organ of unique character that carries him into the super-empirical? Failing this, must he wander sceptical and disillusioned? Or is human experience itself worth while in its purposes and its methods of guidance? Can it organize itself into stable courses or must it be sustained from without? We know the answers of traditional philosophy. They do not thoroughly agree among themselves, but they agree that experience never rises above the level of the particular, the contingent, and the probable. Only a power transcending in origin and content any and all conceivable experience can attain to universal, necessary and certain authority and direction. The empiricists themselves admitted the correctness of these assertions. They only said that since there is no faculty of Pure Reason in the possession of mankind, we must put up with what we have, experience, and make the most possible out of it. They contented themselves with sceptical attacks upon the transcendentalist, with indications of the ways in which we might best seize the meaning and good of the passing moment; or like Locke, asserted that in spite of the limitation of experience, it affords the light needed to guide men's footsteps modestly in conduct. They affirmed that the alleged authoritative guidance by a higher faculty had practically hampered men. It is the function of this lecture to show how and why it is now possible to make claims for experience as a guide in science and moral life which the older empiricists did not and could not make for it.