The whole thought was now present—feeble, scarcely sane, scarcely definite,—but still entire. I proceeded at once, with the
nervous energy of despair, to attempt its execution.
For many hours the immediate vicinity of the low framework
upon which I lay, had been literally swarming with rats. They were
wild, bold, ravenous; their red eyes glaring upon me as if they waited
but for motionlessness on my part to make me their prey. “To what
food,” I thought, “have they been accustomed in the well?”

Why might Poe have kept this information form the readers?