Whatever feeling has an essential characteristic that is agreeable in nature can never also take on one that is disagreeable in nature. It is through some other aspect that the Āryas discredit those [pleasant feelings], so that they will take on a disagreeable quality. For example, they will regard them as the abode of heedlessness, as requiring great exertion to acquire, as undergoing change, and as impermanent.
— Vasubandhu