The intellect, then, does not make truth, neither does it make reality; it makes reality take the form of spatial things, and it makes things seem to be the ground of reality. Were our nature not intellectual, if all consciousness was intuitive, the world would not then appear as things--there would be no things. But, notwithstanding that our world is an illusion, it is not the less on that account a true world, and our science is true knowledge, in the objective meaning of truth, for {73} once an illusion is interpreted, it becomes an integral part of the conception of reality. It would be easy to find abundant illustration of this fact within science itself. Thus in the familiar case of the straight stick which appears bent when partly immersed in water, as soon as the illusion is understood as due to the different refraction of light in media of different density, air and water, it ceases to be an illusion. We then recognise that if a partly immersed stick did not appear bent, it would really be bent. Again, the illusion that clings to us most persistently throughout our experience is that which is connected with movement and rest. The system of movement in which we are ourselves carried along appears to us stationary, while that which is outside it seems alone to move. In very simple cases, such as viewing the landscape from a railway-carriage window, habit has long caused the illusion to cease, but we all remember the child's feeling that the trees and fields were flying past us. The earth's motion never becomes to us a real experience of movement, we accept the fact and never doubt the scientific evidence on which it rests, yet we always speak and think of sunrise and sunset; and this is not merely due to the accident that our language was fixed before the nature of the celestial movement was known, but to a natural illusion which it is far more convenient to retain than to abandon.