There are two concepts which I want to distinguish, and one I call simultaneity and the other instantaneousness.

I hope that the words are judiciously chosen; but it really does not matter so long as I succeed in explaining my meaning.

Simultaneity is the property of a group of natural elements which in some sense are components of a duration.

A duration can be all nature present as the immediate fact posited by sense-awareness.

A duration retains within itself the passage of nature.