One may sometimes discover in his own mind the working of complex tendencies which he has not willed or understood. When one first plans a book he feels but vaguely what material he wants, and collects notes somewhat at random. But as he goes on, if his mind has some synthetic energy, his thought gradually takes on a system, complex yet unified, having a growth of its own, so that every suggestion in this department comes to have a definite bearing upon some one of the many points at which his mind is striving to develop. Every one who has been through anything of this sort knows that the process is largely unintentional and unconscious, and that, as many authors have testified, the growing organism frequently develops with greatest vigor in unforeseen directions. If this can happen right in our own mind, with matters in which we have a special interest, so much the more can it with lines of development to which we are indifferent. As a matter of psychology the evident fact underlying this “working” is that mental development requires the constant stimulus of fresh suggestions, some of which have immensely more stimulating power than others. We know how a word or a glance from a congenial person, the quality of a voice, a poetic or heroic passage in a book, a glimpse of strange life through an open door, a trait of biography, a metaphor, can start a tumult of thought and feeling within us where a moment before there was only apathy. This is “working,” and it seems that something like it runs all through life. It is thus that Greek literature and art have so often awakened the minds of later peoples. The human spirit cannot advance far in any separate channel: there must be a group, a fresh influence, a kindred excitement and reciprocation. These psychical reactions are more like the kindling of a flame, as when you touch a match to fine wood, than they are like the composition of mechanical forces. You might also call it, by analogy, a kind of sexuality or mating of impulses, which unites in a procreative whole forces that are barren in separation. This kindling or mating springs from the depths of life and is not likely to be reduced to formulas. We can see, in a general way, that it grows naturally out of the past. Our primary need is to live and grow, and we are kindled by something that taps the energies of the spirit where they are already pressing for an outlet. We are easily kindled in the direction of our instincts, as an adolescent youth by the sight of a pretty girl, or of our habits, as an archæologist by the discovery of a new kind of burial urn.