Successiveness, Excession, Retaining

A Whiteheadian concept of Successiveness, which any theory of Experience as cumulative seems to entail, construes the sequence of moments A-B as A as an incomplete stage of which B is the completion. But, if B represents a moment of closure, for C to succeed it, the arrival of C must effect a re-opening, via a surpassing of B. Hence, the generation of a new sequence, B-C, requires what can be called a process of 'Excession', by which C goes beyond the hitherto closed moment B. But, the constitution of the succession B-C entails more than a flight of C that leaves B behind--the Excession must be accompanied by a Retaining of B, as well. In other words, Successiveness combines Excession and Retaining. But, Excession is a species of Externalization, and, hence, of Spatialization. Therefore, Successiveness is not a purely Temporal structure.