That to know, in the series of mental phenomena, _what_ are the antecedents, and _what_ their consequents, is one great branch of the Philosophy of Mind, I surely need not attempt to demonstrate; and it would be equally superfluous to demonstrate its importance, especially after the remarks--if even these were necessary,--which I made in a former Lecture; since it is not merely, as a very interesting branch of speculative knowledge, that it is valuable, but, as I then showed, still more valuable, as the foundation of every intellectual art, especially of those noble and almost divine arts, which have, for their immediate object, the illumination and amendment of mankind--the art of training ignorance to wisdom, and even wisdom itself to knowledge still more sublime,--of fixing youthful innocence in the voluntary practice of virtue, that is as yet little more than an _instinct_ of which it is scarcely conscious,--of breathing that moral inspiration, which strengthens feeble goodness, when it is about to fall, tames even the wildest excesses of the wildest passions, and leads back, as if by the invisible power of some guardian spirit, even Guilt itself, to the happiness which it had lost, and the holier wishes, which it rejoices to feel once more. Since the phenomena of the mind, however, are obviously _successive_, like those of matter, the consideration of the sequences of the mental phenomena, and the arrangement of them in certain classes, may appear to you sufficiently analogous to the consideration and arrangement of the sequences of the phenomena of the material world. But that there should be any inquiries, in the philosophy of mind, corresponding with the inquiries into the composition of bodies, may appear to you improbable, or almost absurd; since the mind, and consequently its affections--which I use as a short general term for expressing all the variety of the modes in which it can be affected, and which, therefore, are only the mind itself as it exists in different states,--must be always _simple_ and _indivisible_. Yet, wonderful, or even absurd, as it may seem, notwithstanding the absolute simplicity of the mind itself, and consequently of all its feelings or momentary states,--the Science of Mind is, in its most important respects, a source of analysis, or of a process which I have said to be virtually the same as analysis; and it is only, as it is in this virtual sense analytical, that any discovery, at least that any important discovery, can be expected to be made in it.