What is Art?

I have been reading The Intellectual Life of the Early Renaissance Artist by Francis Ames-Lewis.  I am not very far into it, but it promises to be interesting.  In it Ames-Lewis gives an account of the evolution of the artist from a craftsman/tradesman to an artist with socially elevated standing during the early Renaissance.  He traces the change of paintings from functional objects (stimuli for devotion or decorations for furniture and interiors) into objects that are ends in themselves, with "no self-evident function [and which] appear to serve in an abstract way as visual stimuli to intellectual activity." (p.3)

I think this is a crucial part of the answer to the question What is Art?  It must be a stimuli to intellectual activity. 

Lady with an Ermine, Leonardo da Vinci, Czartoryski Museum, Kraków

John Ruskin expands on this definition in The Two Paths.  Ruskin was writing in 1859, almost one hundred years after the very infancy of the first industrial revolution and in the middle of the second industrial revolution.  It was a time of great technological advancement and an enormous shift in society from agriculture and local production to large scale mass production of manufactured goods.

"It would be well if all students would keep clearly in their mind the real distinction between those words which we use so often, "Manufacture," "Art," and "Fine Art." "MANUFACTURE" is, according to the etymology and right use of the word, "the making of anything by hands,"--directly or indirectly, with or without the help of instruments or machines. Anything proceeding from the hand of man is manufacture; but it must have proceeded from his hand only, acting mechanically, and uninfluenced at the moment by direct intelligence. Then, secondly, ART is the operation of the hand and the intelligence of man together; there is an art of making machinery; there is an art of building ships; an art of making carriages; and so on. All these, properly called Arts, but not Fine Arts, are pursuits in which the hand of man and his head go together, working at the same instant. Then FINE ART is that in which the hand, the head, and the _heart_ of man go together. Recollect this triple group; it will help you to solve many difficult problems. And remember that though the hand must be at the bottom of everything, it must also go to the top of everything; for Fine Art must be produced by the hand of man in a much greater and clearer sense than manufacture is. Fine Art must always be produced by the subtlest of all machines, which is the human hand. No machine yet contrived, or hereafter contrivable, will ever equal the fine machinery of the human fingers. Thoroughly perfect art is that which proceeds from the heart, which involves all the noble emotions;--associates with these the head, yet as inferior to the heart; and the hand, yet as inferior to the heart and head; and thus brings out the whole man."

John Ruskin, A Dalmatian Pelican

And finally, the Art Renewal Center and Fred Ross further codify the definition of art here and in their whole collection of the philosophy behind art:

"Just because something causes you to have a feeling of aesthetic beauty does not make it a work of art.  A work of art is the selective recreation of reality for the purpose of communicating some aspect of what it means to be human or how we perceive the world."  --Fred Ross

Premier Deuil, William Bouguereau, Museo Nacional de Bellas Artes (Buenos Aires, Argentina)