Wie ein Weg im Herbst: Kaum ist er rein gekehrt, bedeckt er sich wieder mit den trockenen Blättern.
Like a path in autumn: scarcely has it been swept clear when it is once more covered with dry leaves. [Kaiser/Wilkins]
Like a path in autumn: no sooner is it cleared than it is once again littered with fallen leaves. [Hofmann]
Perhaps this is offered in preference to the fourteenth aphorism; in this case, the problem is not some enigmatic backsliding, but that the path keeps disappearing. The method, to return to that idea, would be perennial sweeping.
You can't follow someone else down this path, because the leaves erase it behind each one who takes it. The leaves fall steadily as you yourself go down this path, and so, when you turn around, you see no path, only an ocean of leaves. The only bit of the path you can see is the bit directly before you, which you keep clear of leaves with your sweeping, and maybe the last few steps as well, but you don't see where it's going. You can, however, see which direction it seems to be taking.
This is a little like the common idea of time, that is, a moving point of view in the present, rolling down a line, with unavailabilities before and after. But first of all, you can walk wherever you like; this isn't a tightrope high off the ground. Second, there is the added element of methodical effort involved in being at all aware of the path. Did you know where to start sweeping, or did you just sweep here and there until you discovered it?
What are those leaves? Forgetting, not bothering, letting slide.