Three paintings are compared.
As you create your essays, I offer some research and notes to help:
First, you might use Leonardo da Vinci's painting, "Virgin of the Rocks." In terms of its symbolism, you might look at its religious connotations. Although some critics claim that it shows the immaculate conception, others think it recalls the moment when the infant Christ met St John the Baptist" (http://www.bbc.co.uk/science/leonardo/gallery/virgin.shtml).
When looking style and form, you might note its fluidity. Research suggests that "We can always tell a Leonardo work by his treatment of hair, angelic in its fineness, and by the lack of any rigidity of contour. One form glides imperceptibly into another (the Italian term is sfumato), a wonder of glazes creating the most subtle of transitions between tones and shapes" (http://www.artchive.com/artchive/L/leonardo.html).
When looking at aesthetic issues or underlying philosophy, you might look at the hints of Humanism. He uses a rebirth of Latin and Greek classics to emphasize humanity. He also uses a combination of human forms. You might look at its infusion with nature. For example, the peaks of the mountains and the light "reveal the ...
Three pieces from this era are compared.