Think of the universe as an ocean of ether, consisting of layer after layer of varying degrees of vibration under the action of Prana; away from the centre the vibrations are less, nearer to it they become quicker and quicker; one order of vibration makes one plane. Then suppose these ranges of vibrations are cut into planes, so many millions of miles one set of vibration, and then so many millions of miles another still higher set of vibration, and so on. It is, therefore, probable, that those who live on the plane of a certain state of vibration will have the power of recognising one another, but will not recognise those above them. Yet, just as by the telescope and the microscope we can increase the scope of our vision, similarly we can by Yoga bring ourselves to the state of vibration of another plane, and thus enable ourselves to see what is going on there. Suppose this room is full of beings whom we do not see. They represent Prana in a certain state of vibration while we represent another. Suppose they represent a quick one, and we the opposite. Prana is the material of which the: are composed, as well as we. All are parts of the same ocean of Prana, they differ only in their rate of vibration. If I can bring myself to the quick vibration, this plane will immediately change for me: I shall not see you any more; you vanish and they appear.