I should define each kind of knowledge as an organic whole and soundness as the complete possession of all the essential parts. For example, soundness in violin-playing consists in being able to play the notes in all the positions, in tune, and with a pure intonation, whatever may be the degree of rapidity indicated by the musical composer. Soundness in painting consists in being able to lay a patch of color having exactly the right shape and tint. Soundness in the use of language consists in being able to put the right word in the right place. In each of the sciences, there are certain elementary notions without which sound knowledge is not possible, but these elementary notions are more easily and rapidly acquired than the elaborate knowledge or confirmed skill necessary to the artist or the linguist. A man may be a sound botanist without knowing a very great number of plants, and the elements of sound botanical knowledge may be printed in a portable volume. And so it is with all the physical sciences; the elementary notions which are necessary to soundness of knowledge may be acquired rapidly and at any age. Hence it follows that all whose leisure for culture is limited, and who value soundness of knowledge, do wisely to pursue some branch of natural history rather than languages or the fine arts. It is well for every one who desires to attain a perfect economy of time, to make a list of the different pursuits to which he has devoted himself, and to put a note opposite to each of them indicating the degree of its unsoundness with as little self-delusion as may be. After having done this, he may easily ascertain in how many of these pursuits a sufficient degree of soundness is attainable for him, and when this has been decided he may at once effect a great saving by the total renunciation of the rest. With regard to those which remain, and which are to be carried farther, the next thing to be settled is the exact limit of their cultivation. Nothing is so favorable to sound culture as the definite fixing of limits. Suppose, for example, that the student said to himself "I desire to know the flora of the valley I live in," and then set to work systematically to make a herbarium illustrating that flora, it is probable that his labor would be more thorough, his temper more watchful and hopeful, than if he set himself to the boundless task of the illimitable flora of the world. Or in the pursuit of fine art, an amateur discouraged by the glaring unsoundness of the kind of art taught by ordinary drawing-masters, would find the basis of a more substantial superstructure on a narrower but firmer ground. Suppose that instead of the usual messes of bad color and bad form, the student produced work having some definite and not unattainable purpose, would there not be, here also, an assured economy of time? Accurate drawing is the basis of soundness in the fine arts, and an amateur, by