what is expressed by the word 'I': and since I am at the same time in all my sensations, conceptions, and states of consciousness, thought is everywhere present, and is a category that runs through all these modifications. Our first impression when we use the term thought is of a subjective activity--one amongst many similar faculties, such as memory, imagination and will. Were thought merely an activity of the subject-mind and treated under that aspect by logic, logic would resemble the other sciences in possessing a well-marked object. It might in that case seem arbitrary to devote a special science to thought, whilst will, imagination and the rest were denied the same privilege. The selection of one faculty however might even in this view be very well grounded on a certain authority acknowledged to belong to thought, and on its claim to be regarded as the true nature of man, in which consists his distinction from the brutes. Nor is it unimportant to study thought even as a subjective energy. A detailed analysis of its nature would exhibit rules and laws, a knowledge of which is derived from experience. A treatment of the laws of thought, from this point of view, used once to form the body of logical science. Of that science Aristotle was the founder. He succeeded in assigning to thought what properly belongs to it. Our thought is extremely concrete: but in its composite contents we must distinguish the part that properly belongs to thought, or to the abstract mode of its action. A subtle spiritual bond, consisting in the agency of thought, is what gives unity to all these contents, and it was this bond, the form as form, that Aristotle noted and described. Up to the present day, the logic of Aristotle continues to be the received system. It has indeed been spun out to greater length, especially by the labours of the medieval Schoolmen who, without making any material additions, merely refined in details. The moderns also have left their mark upon this logic, partly by omitting many points of logical doctrine due to Aristotle and the Schoolmen, and partly by foisting in a quantity of psychological matter. The purport of the science is to become acquainted with the procedure of finite thought: and, if it is adapted to its pre-supposed object, the science is entitled to be styled correct. The study of this formal logic undoubtedly has its uses. It sharpens the wits, as the phrase goes, and teaches us to collect our thoughts and to abstract --whereas in common consciousness we have to deal with sensuous conceptions which cross and perplex one another. Abstraction moreover implies the concentration of the mind on a single point, and thus induces the habit of attending to our inward selves. An acquaintance with the forms of finite thought may be made a means of training the mind for the empirical sciences, since their method is regulated by these forms: and in this sense logic has been designated Instrumental.