In the oft-quoted words of Frost, “Something there is that doesn’t love a wall, that wants it down.”In this case, I have a strong suspicion that the “something” has four paws, whiskers, and a fluffy tail. I have no hard evidence, but from the way it toppled, it looks like the something was swaying or pulling it over from the top. (“I could say ‘elves’,” said Frost, “but it’s not elves exactly.” Exactly, Max?)
Or of course it could just be that, as I said, the pile was subpar, and not up to Virgo standards.
Thoreau quoted his plow-driver as saying that wood is a fuel that warms you twice. This does not take into account the possibility of having to re-build your wood pile… thrice may suffice.