From Longinus (or whoever):
Images, moreover, contribute greatly, my young friend, to dignity, elevation, and power as a pleader. In this sense some call them mental representations. In a general way the name of image or imagination is applied to every idea of the mind, in whatever form it presents itself, which gives birth to speech. (…)Further, you will be aware of the fact that an image has one purpose with the orators and another with the poets, and that the design of the poetical image is enthralment, of the rhetorical–vivid description. Both, however, seek to stir the passions and the emotions. (Chapter XV, Part 2)
With Cormac McCarthy it has always been a dual purpose. The description is always vivid, especially so with his story world environment. But it is truly stirring as well:
The snow had stopped. Scout was standing in snow to his belly, gazing out at the fantastic landscape with his bleary eyes. Across the yard, brilliant against the facade of pines beyond, a cardinal shot like a drop of blood. (The Orchard Keeper, p. 133)
Once we’ve been led through McCarthy’s landscape and have come to see the expanse of it from the top of the mountain through Uncle Ather’s eyes, we place within it the flaws, the body rotting in the pit of green scum, the brown muddy water of the hurrying creek, and the comings and goings of Rattner and Sylder making their way through this world. A cardinal becomes more than a bird; it is a blood-red reminder of life and death.