This would prove that the people who built Karnac and the Pyramids, who raised to an elevation of about 500 feet blocks of granite, one of which would require fifteen horses to drag it along a level road, who placed these enormous stones side by side without mortar or cement of any kind and with almost invisible joints, who possessed the secret of malleable glass and of painting in colours that have not faded even after the lapse of centuries ... that such a race of men were inferior to the rude, uncultured Merovingians, and scarcely the equals of the Polynesians! Science also tells us that in a child five years of age the human brain weighs, on an average, 1250 grammes--this, too, would bear no relation whatever with the intellectual and moral development of a child of that age and that of an adult man. Though Cuvier's brain weighed 1830 grammes, and Cromwell's 2230, that of Tiedemann, the great anatomist, when placed on the scales, weighed no more than 1254, and that of Gambetta only 1246. The physical body of itself can give no reason for a host of psychological phenomena on which, however, a flood of light is shed if one recognises the existence of other vehicles of consciousness possessing more far-reaching vibrations, and consequently capable of expressing higher faculties. During sleep, for instance, which is characterised by the Ego having left his physical body, reason is absent, and what we call dreams are generally nothing but a tissue of nonsense, at which the dreamer feels astonishment only when returning to his body on awaking. On the other hand, as we have seen in Chapter I., when the Ego succeeds in imprinting on the brain the vibrations of the higher consciousness, it is able to regain the memory of facts long forgotten and to solve problems that could not be solved during the waking state. There are madmen who have ceased to be mad during somnambulism; persons of rudimentary intelligence have proved themselves to be profound thinkers during the mesmeric trance; when under somnambulism vision is possible to those born blind and certain people can see things that are happening a great distance away, and their reports have been proved correct; certain phenomena of double-consciousness cannot be explained without the plurality--the duality, at all events--of the vehicles of consciousness.