We do our talking with one side of the brain only. But talking is somewhat intimately connected with thinking. We ought to always, we generally do, think before we speak; while much of our thinking, and on the whole the most important part, consists in saying over words to ourselves.

Speech and thinking, then, go so often together, that it becomes a great convenience to get the thinking done also on one side of the head only, and on the same side with the speech. It might have been either side; it did happen to be the left. One cannot say why, any more than why the heart should be on the left side and the liver on the right, or why some snail shells curl one way and some the other. But at any rate it is the left side.

Now I don’t know whether you have yet been taught in your school physiology, if you have not yet you will be shortly, that the nerves which run from the brain to various parts of the body, cross over to the other side from the one on which they start. Thus the right side of the brain controls the left side of the body; while the left side of the brain controls the right side of the body.

But if the thinking is all done on the left side of the head, which hand will act more quickly on the thought? Evidently, the right hand; messages for that hand travel directly along the nerves, crossing sides once. Therefore we are right-handed.

Some people, however, are born with the “speech center,” as it is called, on the right side of the head instead of on the left. For such persons the most direct path is to the left hand. These persons, then, are naturally left-handed. The difference, therefore, between a right-handed and a left-handed person is not so much in the side of the body with which they have learned to act, as in the side of the brain with which they have learned to think. But the animals, who think on both sides alike, also use either forefoot equally well, and are neither right nor left-handed.

This talking on one side of the brain has another curious result. Did you ever stop to think why a right-handed batter stands with his left side to the ball? Or why a driver of a horse sits on the right hand end of the seat? Or why the engineer of a locomotive sits on the right side of the cab, altho this position forces him to use his left hand for the throttle valve? Or why you sight a gun or look thru a spy-glass with the right eye? Or why you draw a bow with the right hand on the string?

It is all on account of this same one-sided speech center. This has made us right-handed; it has also made us right-eyed. We think much in words; but we also think much about how things look. We think most quickly concerning messages which come in on the thinking side of the brain; and those are from the right eye, since the eye nerves, like those from the hand, cross sides on the way. So hand and eye and speech and thought all use the same side of the head; and sight and thought and action follow one another most easily. Being then right-eyed, we stand to bat, or sit to drive, or use gun or bow or telescope, in the way which gives the better sight to the better eye. But of course, naturally left-handed people are also naturally left-eyed.

Some people, however, are as we say, ambidextrous; that is, they use both hands about equally well, just as all animals do. Nobody, however, is ever naturally ambidextrous. Sometimes the ambidexters are people who have hurt the right hand, and had to learn to use the left. More often they are persons naturally left-handed who have been taught to use the right hand more than is natural in an effort to make them right-handed, tho of course they really are just as left-handed at ever, since no use of the other hand will change over the speech center. But some ambidexters, oddly enough, are made so by an injury to the sight of the right eye, if they were right-handed to begin with, or to the left eye if they were left-handed. Hand and eye have so often to work together and work quickly, that one tends to use the hand on the side of the better eye, even when that is the wrong side.

At any rate, tho it is an excellent plan to learn to do all heavy work equally well on either side of the body and with either hand, fine work and quick work and thinking work had better be done with the hand that does it most naturally. This keeps writing, thinking, speaking, memory, and the rest all close together, on one side of the head, handy to one another, instead of scattering them about, some on the wrong side of the body, some on the right.