Mind in its purest play is like some bat That beats about in caverns all alone, Contriving by a kind of senseless wit Not to conclude against a wall of stone. It has no need to falter or explore; Darkly it knows what obstacles are there, And so may weave and flitter, dip and soar In perfect courses through the blackest air. And has this simile a like perfection? The mind is like a bat. Precisely. Save That in the very happiest of intellection A graceful error may correct the cave.