It's an old epistemological debate, older, actually, than the koan about the tree in the forest. Plato weighed in on it, and philosophers for two millennia afterward: What is beauty? Is it a measurable fact (Gottfried Leibniz), or merely an opinion (David Hume), or is it a little of each, colored by the immediate state of mind of the observer (Immanuel Kant)?...Context matters.