Wikipedia: art is expressive work intended to be appreciated for its beauty or emotional power; or the process of creating such a work.
Venus of Willendorf
c. 25,000 years ago (Upper Paleolithic)
Although this is usually thought to be a fertility goddes/figure, there is an interesting article suggesting that this figure and other prehistoric "Venus figures" are self-portraits made by women looking down at their own bodies. Read it here.
Self-portrait as the Allegory of Painting
Artemisia Gentilesci, c. 1639. Oil on canvas.
Cornaro Chapel, The Ecstacy of Saint Teresa
Gian Lorenzo Bernini, Rome, 1647-52. Marble.
Made as part of the Counter-Reformation movement, this chapel features the Spanish mystic Teresa experiencing a vision from God. In her writing she says: "I saw in his hand a long spear of gold, and at the iron's point there seemed to be a little fire. He appeared to me to be thrusting it at times into my heart, and to pierce my very entrails; when he drew it out, he seemed to draw them out also, and to leave me all on fire with a great love of God. The pain was so great, that it made me moan; and yet so surpassing was the sweetness of this excessive pain, that I could not wish to be rid of it. The soul is satisfied now with nothing less than God."