In seeking to appreciate whereby it differs perhaps we shall gain more than by vainly seeking points of resemblance. We shall discover, in fact, behind the insect and its prodigious instincts, a vast and remote horizon, a region at once more profound, more extensive, and more fruitful than that of the intelligence; and if Fabre is able to help us to decipher a few pages of "the most difficult of all volumes, the book of ourselves," it is precisely, as a philosopher told him, because "man has remained instinctive in process of becoming intelligent." (8/2.) The work of Fabre is from this point of view an invaluable treasury of observations and experiments, and the richest contribution which has ever been made to the study of these fascinating problems. "The function of the intelligence is to reflect, to be conscious; that is, to relate the effect to its cause, to add a "because" to a "why"; to remedy the accidental; to adapt a new course of conduct to new circumstances." In relation to the human intelligence thus defined Fabre has considered these nervous aptitudes, so well adjusted, according to the evolutionists, by ancient habit, that they have finally become impulsive and unconscious, and, properly speaking, innate. He has demonstrated, with an abundance of proof and a power of argument that we must admire, the blind mechanism which determines all the manifestations, even the most extraordinary, of that which we call instinct, and which heredity has fixed in a species of unchangeable automatism, like the rhythm of the heart and the lungs. (8/3.) Let us, from this wealth of material, from among the most suggestive examples, select some of his most striking demonstrations, which are classics of their kind. Fabre has not attempted to define instinct, for it is indefinable; nor to probe its essential nature, which is impenetrable. But to recognize the order of nature is in itself a sufficiently fascinating study, without striving to crack an unbreakable bone or wasting time in pondering insoluble enigmas. The important matter is to avoid the introduction of illusions, to beware of exceeding the data of observation and experiment, of substituting our own inferences for the facts, of outstripping reality and amplifying the marvellous. Let us listen to the scrupulous analysis whose lessons, scattered through four thousand pages, teach us more concerning instinct and its innumerable variations than all the most learned treatises and speculations of the philosophers. Nothing in the world perplexes the mind of the observer like the spectacle of the birth and growth of the instincts. At precisely the right moment, just as failure or disaster seems foreordained by the previously established circumstances, Fabre shows us his insects as suddenly mastered by an irresistible force.