The wave offering is a real transaction of light in the head, the pineal gland sending its fine pulse upward and receiving one back, an offer and a confirmation passing between a person and the divine. This is why it must be waved and not merely laid down: a wave is what moves between 2 who are speaking without words. The breast is the pituitary, the gland that pours the inner milk of nourishment, and it is lifted with the fat, the richness of the animal nature, so that the whole lower supply is offered up through fire, which is spirit, the higher heat that receives it.
One's own hands bring it because no priest outside can perform this exchange for you. It happens within, as the glands of the head answer each other and the person becomes the altar where the wave rises and returns.
Breast: the pituitary gland, source of the inner milk that feeds the higher body
Fat: the density and richness of the animal nature, gathered up to be surrendered in the flame
Fire: spirit, the higher heat that consumes the lower offering and lifts it