Talking of the fact as a “complex of objects” springs from this confusion (cf Tractatus Logico-philosophicus). Supposing we asked: “How can one imagine what does not exist?” The answer seems to be: “If we do, we imagine non-existent combinations of existing elements”. A centaur doesn't exist, but a man's head and torso and arms and a horse's legs do exist. “But can't we imagine an object utterly different from any one which exists?” ‒ ‒ ‒ We should be inclined to answer: “No; the elements, individuals, must exist. If redness, roundness and sweetness did not exist, we could not imagine them”.