The one peculiar attribute we find in time, space, and causation is that they cannot exist separate from other things. Try to think of space without colour, or limits, or any connection with the things around — just abstract space. You cannot; you have to think of it as the space between two limits or between three objects. It has to be connected with some object to have any existence. So with time; you cannot have any idea of abstract time, but you have to take two events, one preceding and the other succeeding, and join the two events by the idea of succession. Time depends on two events, just as space has to be related to outside objects. And the idea of causation is inseparable from time and space. This is the peculiar thing about them that they have no independent existence. They have not even the existence which the chair or the wall has. They are as shadows around everything which you cannot catch. They have no real existence; yet they are not non-existent, seeing that through them all things are manifesting as this universe. Thus we see, first, that the combination of time, space, and causation has neither existence nor non-existence. Secondly, it sometimes vanishes. To give an illustration, there is a wave on the ocean. The wave is the same as the ocean certainly, and yet we know it is a wave, and as such different from the ocean. What makes this difference?