This trinity is composed (i) of the temporal series of extensionless instants, (ii) of the aggregate of material entities, and (iii) of space which is the outcome of relations of matter.
There is a wide gap between these presuppositions of the intellectual theory of materialism and the immediate deliverances of sense-awareness.
I do not question that this materialistic trinity embodies important characters of nature.

But it is necessary to express these characters in terms of the facts of experience.

This is exactly what in this lecture I have been endeavouring to do so far as time is concerned; and we have now come up against the question, Is there only one temporal series?
The uniqueness of the temporal series is presupposed in the materialist philosophy of nature.

But that philosophy is merely a theory, like the Aristotelian scientific theories so firmly believed in the middle ages.
If in this lecture I have in any way succeeded in getting behind the theory to the immediate facts, the answer is not nearly so certain.

The question can be transformed into this alternative form, Is there only one family of durations?
In this question the meaning of a 'family of durations' has been defined earlier in this lecture.