Thus, the mistress of the house knows that when her thoughts are free to take their own course, they run to cares of the house or the larder, to tomorrow’s dinner or the winter’s clothing; that is, thought runs into the rut which has been, so to speak, worn for it by constant repetition. The mother’s thoughts run on her children, the painter’s on pictures, the poet’s on poems; those of the anxious head of the house on money cares, it may be, until in times of unusual pressure the thoughts beat, beat, beat in that well-worn rut of ways and means, and decline to run in any other channel, till the poor man loses his reason, simply because he cannot get his thoughts out of that one channel made in the substance of his brain. And, indeed, “that way madness lies” for every one of us, in the persistent preying of any one train of thought upon the brain tissue. Pride, resentment, jealousy, an invention that a man has laboured over, an opinion he has conceived, any line of thought which he has no longer the power to divert, will endanger a man’s sanity.