That is to say, the act of coition is the essential clue to sex.
Now does all life work up to the one consummating act of coition?
In one direction, it does, and it would be better if psychoanalysis plainly said so.

In one direction, all life works up to the one supreme moment of coition.

Let us all admit it, sincerely.
But we are not confined to one direction only, or to one exclusive consummation.

Was the building of the cathedrals a working up towards the act of coition?
Was the dynamic impulse sexual?
No.

The sexual element was present, and important.