The story which such animal experience contains, however, needs only to be better articulated in order to disclose its underlying machinery. The figures even of that disordered drama have their exits and their entrances; and their cues can be gradually discovered by a being capable of fixing his attention and retaining the order of events. Thereupon a third step is made in imaginative experience. As pleasures and pains were formerly distributed among objects, so objects are now marshalled into a world. _Felix qui potuit rerum cognoscere causas_, said a poet who stood near enough to fundamental human needs and to the great answer which art and civilisation can make to them, to value the Life of Reason and think it sublime. To discern causes is to turn vision into knowledge and motion into action. It is to fix the associates of things, so that their respective transformations are collated, and they become significant of one another. In proportion as such understanding advances each moment of experience becomes consequential and prophetic of the rest. The calm places in life are filled with power and its spasms with resource. No emotion can overwhelm the mind, for of none is the basis or issue wholly hidden; no event can disconcert it altogether, because it sees beyond. Means can be looked for to escape from the worst predicament; and whereas each moment had been formerly filled with nothing but its own adventure and surprised emotion, each now makes room for the lesson of what went before and surmises what may be the plot of the whole. At the threshold of reason there is a kind of choice. Not all impressions contribute equally to the new growth; many, in fact, which were formerly equal in rank to the best, now grow obscure. Attention ignores them, in its haste to arrive at what is significant of something more. Nor are the principles of synthesis, by which the aristocratic few establish their oligarchy, themselves unequivocal. The first principles of logic are like the senses, few but arbitrary. They might have been quite different and yet produced, by a now unthinkable method, a language no less significant than the one we speak. Twenty-six letters may suffice for a language, but they are a wretched minority among all possible sounds. So the forms of perception and the categories of thought, which a grammarian’s philosophy might think primordial necessities, are no less casual than words or their syntactical order. Why, we may ask, did these forms assert themselves here? What principles of selection guide mental growth? [Sidenote: Attention guided by bodily impulse.]