How does Federico Garcia Lorca use imagery in Blood Wedding?

The imagery throughout is that of the Earth itself, of the fundamental categories of existence: the knife and associated images from the mineral kingdom (the silver dagger stuck in the horse's eyes, the pins from the bridal wreath, the glass splinters stuck in the tongue of the Bride, the nails, the metal chain, the frost and snow, the Moon, the ashes); from the vegetable kingdom the flowers, weeds, wheat, bread with which the fathers and sons of men are identified (Man is a "mirror of the earth"); and from the animal kingdom the man himself, inseparable from his horse; the woman associated with the serpent; the birds.