It has also another disadvantage.

With the assumption of this fourth case the distinction between space and time becomes unduly blurred.

The whole object of these lectures has been to enforce the doctrine that space and time spring from a common root, and that the ultimate fact of experience is a space-time fact.

But after all mankind does distinguish very sharply between space and time, and it is owing to this sharpness of distinction that the doctrine of these lectures is somewhat of a paradox.

Now in the third assumption this sharpness of distinction is adequately preserved.