"The dove is the loveliest and most striking symbol of the Holy Spirit. Its form and color put us in mind of the grace and purity of the Holy Spirit, its rapid but unagitated flight represents His lively yet controlled motion, its low murmur is like the expression of love which we have come to associate with the Holy Spirit. Following the baptism in the Jordan, the dove hovered between the Father and His incarnate Son, descending from the former to the latter. Thus in eternity, in virtue of His relation to the Father and the Son, the Holy Spirit hovers above and between them; He shelters them, as it were, under His wings, and brings them together in Himself in blissful embrace, crowning and perfecting their love."
-Matthias Scheeben in The Mysteries of Christianity.