Little as the modern representatives of the Schoolmen are satisfied, either with the spirit of Mr. Mill's demand, or with the mode of his own response to it, they have deemed it well worth while, not indeed to change the old Logic, but to add to it a new book. Pure Logic remains substantially what it was, and is justified in its position. It assumes, as all other sciences do and must, that human thought has, in general, objective reality; and on this most legitimate assumption it proceeds to lay down the laws of orderly, consistent thinking. The newly added part of Logic, often called Material, Applied or Critical, takes for its special purpose to defend the objective reality of thought. It is thus an assertion of a form of realism, as against idealism, and is called in this book the Philosophy of Certitude. For the whole question comes to this: what reasonable account can be given of man's claim to have real certainty about things? What are the ultimate grounds for holding, that man may regard his knowledge about objects as undoubtedly correct? Scientifically to draw out the account here demanded is a work appositely described by the title, The First Principles of Knowledge. Manuals of Catholic philosophy by John Rickaby.