which we have been conscious in the past, and by selecting or abstracting from the mental images so compared the points in which they resemble each other. The points of resemblance thus selected or abstracted from a number of particulars compose what we call an abstract or general idea, and from a comparison of such abstract or general ideas with each other we arrive at general conclusions, which define the relations of the ideas to each other. Experience in general consists in the whole body of conclusions thus deduced from a comparison of all the particular sensations, emotions, and ideas which make up the conscious life of the individual. Hence in order to constitute experience the mind has to perform a more or less complex series of operations, which are commonly referred to certain mental faculties, such as memory, imagination, and judgment. This analysis of experience does not pretend to be philosophically complete or exact; but perhaps it is sufficiently accurate for the purpose of these lectures, the scope of which is not philosophical but historical.

Two kinds of experience, the experience of our own mind and the experience of an external world.

Now experience in the widest sense of the word may be conveniently distinguished into two sorts, the experience of our own mind and the experience of an external world. The distinction is indeed, like the others with which I am dealing at present, rather practically useful than theoretically sound; certainly it would not be granted by all philosophers, for many of them have held that we neither have nor with our present faculties can possibly attain to any immediate knowledge or perception of an external world, we merely infer its existence from our own sensations, which are as strictly a part of our mind as the ideas and emotions of our waking life or the visions of sleep. According to them, the existence of matter or of an external world is, so far as we are concerned, merely an hypothesis devised to explain the order of our sensations; it never has been perceived by any man, woman, or child who ever lived on earth; we have and can have no immediate knowledge or perception of anything but the states and operations of our own mind. On this theory what we call the world, with all its supposed infinitudes of space and time, its systems of suns and planets, its seemingly endless forms of inorganic matter and organic life, shrivels up, on a close inspection, into a fleeting, a momentary figment of thought. It is like one of those glass baubles, iridescent with a thousand varied and delicate hues, which a single touch suffices to shatter into dust. The philosopher, like the sorcerer, has but to wave his magic wand,