Day 31 - Leviticus 4-7

Not without reason are "a pair of turtledoves and two young doves" accepted in the sacrifices. For they are worth the same, and you never find separate mention of just a pair of doves but "a pair of turtledoves and two young doves." The dove denotes the Holy Spirit. But when the great and more hidden mysteries are in question and the things that many people cannot grasp, then the Holy Spirit is represented under the appellation of a turtledove—of the bird, that is to say, that always dwells on mountain ridges and in the tops of trees. But in the valleys, in the things that all men understand, he figures as a dove―Origen