When you think of the Renaissance, the names that come to mind are probably the artists of this period: Leonardo and Michelangelo, for instance. And when you think of the greatest work of art in the western world, Michelangelo's Sistine Ceiling might come to mind. This is a period of big, ambitious projects.
How is the High Renaissance different from the Early Renaissance?
As the Humanism of the Early Renaissance develops, a problem arises. Have a look at Fra Filippo Lippi's Madonna and Child with Angels. We see a Madonna and Christ Child that have become so real—the figures so human—that in some ways we can hardly tell that these are spiritual figures (except perhaps for the faint outline of a halo, and Mary's sorrowful expression and hands clasped in prayer). On the other hand, in the Middle Ages, the need to create transcendent spiritual figures, meant a move toward abstraction, toward flatness and elongation.
In the Early Renaissance then, a tension arises—to create spiritual figures, your image can't look very real, and if you want it to appear real, then you sacrifice some spirituality. In the late 15th century though, Leonardo da Vinci creates figures who are physical and real (just as real as Lippi's or Masaccio's figures) and yet they have an undeniable and intense spirituality. Leonardo unites the real and spiritual, or soul and substance.
The best way to see this, is in this painting by Verrocchio, an important artist who Leonardo was apprenticed to when he was young.
Verocchio asked Leonardo to paint one of the angels in his paining of the Baptism of Christ, that we see here. Can you tell which angel is Leonardo's? One angel should look more like a boy—that's the Early Renaissance angel (the one painted by Verrocchio) and the other angel should look like a High Renaissance angel, like a spiritual figure—truly like an angel sent by God from heaven (that's Leonardo's angel).
Leonardo's angel is ideally beautiful and moves in a graceful and complex way, twisting to the left but raising her head up and to the right. Figures that are both elegant and ideally beautiful are a key characteristic of the High Renaissance.