The herd instinct, for example, is of many sorts. It has two main divisions, the fear-instinct, and the aggressive instinct. But the vengeance instinct is not part of the herd instinct. But consider the mode of communication of herd instinct. The communication between the individuals in a herd is not through the _mind_. It is not through anything said or known. It is sub-mental. It is telepathic. Why does a flock of birds rise suddenly from the treetops, all at once, in one spring, and swirl round in one cloud towards the water? There was no visible sign or communication given. It was a telepathic communication. They sat and waited, and waited, and let the individual mind merge into a kind of collective trance. Then click!--the unison was complete, the knowledge or suggestion was one suggestion all through, the action was one action. This so-called telepathy is the clue to all herd instinct. It is not instinct. It is a vertebral-telegraphy, like radio-telegraphy. It is a complex interplay of vibrations from the big nerve-centres of the vertebral system in all the individuals of the flock, till, click!--there is a unanimity. They have one mind. And this one-mindedness of the many-in-one will last while ever the peculiar pitch of vertebral nerve-vibrations continues unbroken through them all. As the vibration slacks off, the flock falls apart. This vertebral telepathy is the true means of communication between animals. It is perhaps most highly developed where the brain, the mental consciousness, is smallest. Indeed the two forms of consciousness, mental and vertebral, are mutually exclusive. The highest form of vertebral telepathy seems to exist in the great sperm whales. Communication between these herds of roving monsters is of marvellous rapidity and perfection. They are lounging, feeding lazily, individually, in mid-ocean, with no cohesion. Suddenly, a quick thought-wave from the leader-bull, and as quick as answering thoughts the cows and young bulls are ranged, the herd is taking its direction with a precision little short of miraculous. Perhaps water acts as a most perfect transmitter of vertebral telepathy. This is the famous wisdom of the serpent, this vertebral consciousness and telepathy. This is what makes the magic of a leader like Napoleon--his powers of sending out intense vibrations, messages to his men, without the exact intermediation of mental correspondence. It is not brain-power. In fact, it is, in some ways, the very _reverse_ of brain-power: it might be called the acme of stupidity. It is the stupendous wits of brainless intelligence. A marvellous reversion to the pre-mental form of consciousness.