The nature of my investigations keeps me on a lower and more prosaic level; I wish to arrive at results that are a little more within the range of practical experience. The restricted angle of my vision forbids me to consider, as Guizot does, the measure of prosperity enjoyed by human societies, or to contemplate, with von Humboldt, the high peaks on which a few great minds sit in solitary splendour; my inquiries concern merely the amount of power, material as well as moral, that has been developed among the mass of a people. It has made me uneasy, I confess, to see two of the most famous men of the century losing themselves in by-ways; and if I am to trust myself to follow a different road from theirs, I must survey my ground, and go back as far as possible for my premises, in order to reach my goal without stumbling. I must ask the reader to follow me with patience and attention through the winding paths in which I have to walk, and I will try to illuminate, as far as I can, the inherent obscurity of my subject. There is no tribe so degraded that we cannot discover in it the instinct to satisfy both its material and its moral needs. The first and most obvious difference between races lies in the various ways in which the two sides of this instinct are balanced. Among the most primitive peoples they are never of equal intensity. In some, the sense of the physical need is uppermost, in others, the tendency to contemplation. Thus the brutish hordes of the yellow race seem to be dominated by the needs of the body, though they are not quite without gleams of a spiritual world. On the other hand to most of the negro tribes that have reached the same stage of development, action is less than thought, and the imagination gives a higher value to the things unseen than those that can be handled. From the point of view of civilization, I do not regard this as a reason for placing the negroes on a higher level; for the experience of centuries shows that they are no more capable of being civilized than the others. Ages have passed without their doing anything to improve their condition; they are all equally powerless to mingle act and idea in sufficient strength to burst their prison walls and emerge from their degradation. But even in the lowest stages of human progress I always find this twofold stream of instinct, in which now one, now the other current predominates; and I will try to trace its path as I go up the scale of civilization.