different from the constancy; and whether discoverable or not, is not to be confounded with the existence of that thing, or series of things, of which it is required as the explanation. Take an example. I see a certain person pass along the street before my window every morning at a quarter before nine o’clock, and another person following him regularly at ten minutes before nine. Here is a customary conjunction. If it happened once, or even twice, I should ask no questions, it might have been what men call accidental; but it has happened every day for six months, and I ask the cause. Am I wrong in doing so? Is there no cause? Or do I give a sufficient answer when I say it is a customary conjunction, or an invariable sequence? The invariability of the sequence, so far from offering any explanation of the cause, is the very thing that suggests it. I insist on believing that this invariability has a cause, and that it is neither an accident nor a custom. Of course it may be possible that I shall not be able to find out the cause; but that there is a cause I believe as firmly as that two and two are four. Now why am I entitled to demand a cause here, or in the case of any such conjunction? and what do I mean by it? I mean something that has an inherent and necessary virtue to produce effect; and I am entitled to make the demand, just because I am a reasonable being, and because the exercise of reason has proved to me directly that invariable sequences are not produced except by the persistent application of some calculated force of which energizing reason is the source. I know by experience that whenever this presidency of reason is abolished, the {316} world in which I move instantly becomes a chaos; and the living unity of that mind which I exercise in thinking, and which brings its own unity into the wide sphere of my thoughts, feelings, and actions, displays to me in the most direct way that the unity of plan between the different members of an invariable sequence can proceed only from that of which plan and unity can be predicated, viz., REASON. I derive my notion of cause therefore primarily from the most direct and certain of all sources, from my own existence; and if Mr. Hume objects that I do not know how my mind acts on my body, or how my limb does not follow my will in the case of palsy in the motor nerves, this ignorance does not in the least shake my conviction that a cause is something different from a custom; a piston or a paddle may be deranged, but the steamboat is moved by a cause nevertheless, and that cause is twofold,--the steam, and the mind of James Watt. These conclusions with regard to the works of man even Mr. Hume seems to regard as perfectly justifiable; for, like all puzzle-headed paradox-mongers, he is forced to forget his own distinctions, and to speak of a cause after all, as something different from a custom. We are justified, therefore, in finding in the energizing reason of man a cause, and the only