Practically, though of course not absolutely, they ignore the element of time.

They represent effort and product as being always so nearly simultaneous that, although the former must literally precede the latter, yet, if we estimate life in terms of years, or even months, or weeks, a man has ceased to produce as soon as he has ceased to work.
Now, of certain forms of effort this may be true enough.

A bricklayer, for example, as soon as he ceases to lay bricks, ceases to produce anything.

His wall-building closes its effects with the walls which he himself has built.

It does nothing to facilitate the building of other walls in the future.