It is a favorite simile among writers on education that the mind is not unlike a field, and that the steps of instruction answer to the successive stages of the farmer's work. First there is the preparation of the soil, then come the planting, the cultivating, and in due time the harvest, the mill, and the market. Two of these steps, the preparing and the applying, concern us here; the work of presenting and elaborating is a theme by itself, and has been treated in a separate chapter. 1. Preparing the ground: Approach. The art of "getting a good ready" is an art worth mastering. In sermon or Sunday-school lesson alike the beginning is the main concern. It is a good plan to seem to waste time at the start. Nine tenths plowing, harrowing, marking out, one tenth sowing, and (as we shall see) no looking for a crop at all, is a just proportion for the most of our lessons. We shall be always safe in counting upon a sufficient number of stony-ground hearers to justify us in clearing the ground, and making it mellow with interest and expectation. And even those who would receive the word with gladness cannot take it in unless they have something to grasp it with, cannot hear without something to hear with. And this must be given them by the teacher. We are here at the very heart of the science of teaching. A little two-year-old child will serve us as an example. He is to be put in bed in a strange room, and is to go to sleep alone. Spring the idea upon him and he will reject it. Prepare him for it, by telling him a story of a little boy who went to bed in a new room, a new bed, and all alone, and he is eager for the hour of bed-time. When the time comes, the picture already in his mind, of a little boy, a new room, a peaceful going to bed, welcomes the actual experience, point for point. The wise mother has made a nest for the experience. So might a teacher prepare the minds of his pupils to receive the idea of ninety millions of miles. "If any one there in the sun fired off a cannon straight at you, what should you do?" "Get out of the way," would be the answer. "No need of that," the teacher might reply. "You may quietly go to sleep in your room, and get up again; you may learn a trade, and grow as old as I am--then only will the cannon-ball be getting near, then you may jump to one side! See, so great as that is the sun's distance!" So writes a German teacher--explaining the law of apperception, of making a nest for the idea. We cannot understand--cannot even see or hear--the absolutely new. Every new plan or way of looking at things, or doctrine, is received into the mind on one condition only--that it be introduced by a comrade already there. Then when the new idea calls from without, its fellow answers from within, and an entrance is effected.