As the will has equipped itself with every organ and every weapon, offensive as well as defensive, so has it likewise provided itself in every animal shape with an _intellect_, as a means of preservation for the individual and the species. It was precisely in this account that the ancients called the intellect the ἡγεμονικόν, _i.e._ the guide and leader. Accordingly the intellect, being exclusively destined to serve the will, always exactly corresponds to it. Beasts of prey stood in greater need of intellect, and in fact have more intelligence, than herbivorous animals. The elephant certainly forms an exception, and so does even the horse to a certain extent; but the admirable intelligence of the elephant was necessary on account of the length of its life (200 years) and of the scantiness of its progeny, which obliged it to provide for a longer and surer preservation of the individual: and this moreover in countries teeming with the most rapacious, the strongest and the nimblest beasts of prey. The horse too has a longer life and a scantier progeny than the ruminants, and as it has neither horns, tusks, trunk, nor indeed any weapon save perhaps its hoofs, it needed greater intelligence and swiftness in order to elude pursuit. Monkeys needed their extraordinary intelligence, partly because of the length of their life, which even in the moderate-sized animal extends to fifty years; partly also because of their scanty progeny, which is limited to one at a time, but especially because of their _hands_, which, to be properly used, required the direction of an understanding. For monkeys depend upon their hands, not only for their defence by means of outer weapons such as sticks and stones, but also for their nourishment, this last necessitating a variety of artificial means and a social and artificial system of rapine in general, the passing from hand to hand of stolen fruit, the placing of sentinels, &c. &c. Add to this, that it is especially in their youth, before they have attained their full muscular development, that this intelligence is most prominent. In the _pongo_ or ourang-outang for instance, the brain plays a far more important part and the understanding is much greater during its youth than at its maturity, when the muscular powers having attained full development, they take the place of the proportionately declining intellect. This holds good of all sorts of monkeys, so that here therefore the intellect acts for a time vicariously for the yet undeveloped muscular strength. We find this process discussed at length in the "Résumé des Observations de Fr. Cuvier sur l'instinct et l'intelligence des animaux," par Flourens (1841), from which I have quoted the whole passage referring to this question in the second volume of my chief work, at the end of the thirty-first chapter, and this is my only reason for not repeating it here. On the whole, intelligence gradually increases from the rodents[235] to