This system, which first rose at the suggestion of Lord Bacon, on the ruins of the school-philosophy, has been gradually growing up to its present height ever since, from a wrong interpretation of the word _experience_, confining it to a knowledge of things without us; whereas it in fact includes all knowledge, relating to objects either within or out of the mind, of which we have any direct and positive evidence. We only know that we ourselves exist, the most certain of all truths, from the experience of what passes within ourselves. Strictly speaking, all other facts of which we are not immediately conscious, are such in a secondary and subordinate sense only. Physical experience is indeed the foundation and the test of that part of philosophy which relates to physical objects: farther, physical analogy is the only rule by which we can extend and apply our immediate knowledge, or infer the effects to be produced by the different objects around us. But to say that physical experiment is either the test, or source, or guide of that other part of philosophy which relates to our internal perceptions, that we are to look in external nature for the form, the substance, the colour, the very life and being of whatever exists in our minds, or that we can only infer the laws which regulate the phenomena of the mind from those which regulate the phenomena of matter, is to confound two things entirely distinct. Our knowledge of mental phenomena from consciousness, reflection, or observation of their correspondent signs in others is the true basis of metaphysical inquiry, as the knowledge of _facts_, commonly so called, is the only solid basis of natural philosophy. To assert that the operations of the mind and the operations of matter are in reality the same, so that we should always regard the one as symbols or exponents of the other, is to assume the very point in dispute, not only without any evidence, but in defiance of every appearance to the contrary.