For we can imagine thoughts related in time without any perception of nature.

For example we can imagine one of Milton's angels with thoughts succeeding each other in time, who does not happen to have noticed that the Almighty has created space and set therein a material universe.

As a matter of fact I think that Milton set space on the same absolute level as time.

But that need not disturb the illustration.

In the second place it is difficult to derive the true serial character of time from the relative theory.