Saint Thomas wrote to be beautiful all that whose apprehension pleases. We understand by apprehension the capture through the senses, understanding or heart. You can also say to be lovely or beautiful that whose contemplation pleases.
It is pleasant to contemplate a Velázque’s painting, listen to a Mozart’s symphony, feel some verses from Antonio Machado and stare at a sunset.
The pleasure produced by beautiful things is spiritual, pure and uninterested. A Goya’s painting provides pleasure to all visitors and does not ended of providing that pleasure. The painting remains. However, a delicacy provides pleasure to only one: who eats it and consumes it.