"The revelation of this mystery in its character of extraordinary proof of the divine love for us, calls for a boundless gratitude and return of love; but the mystery itself must be much more effective in enkindling in us a supernatural, childlike love of God. The natural creature knows God rather as the absolute Being on whom every other being depends; and the Old Testament reveals God as He who is, without whom nothing is, and who therefore is enthroned above us as the absolute Lord of all beings. As such, of course, God deserves our love, too, because He makes His goodness known also by giving existence to other beings. But the wealth of the divine goodness comes into prominence only in the divine Trinity. Here God appears to us in eternal, necessary, absolute surrender and communication of His entire essence; here we perceive that He is good not only because He possesses infinite goods, but that He is good, infinitely good, in the complete communication of His goods. Does He not appear immeasurably more lovable now than before? Must not our love for Him become incomparably more ardent and tender, when we see how the Father gives His entire essence to the Son, and then remains united with His Son in so stupendous a love that a third person proceeds from that love, a person in whom they embrace each other? No wonder that with Christianity, which first ushered a clear knowledge of the Trinity into the world, a new source of divine love, such as had never been know before, burst forth in the world, that in place of the reverential awe in presence of the Supreme Being which had ruled in the Old Testament, the law of servitude, an enchanting and joyous wonderment at the divine goodness made its appearance. Undoubtedly the consideration that God the Father had given His only-begotten Son to the world out of love for it contributed to this. But this mission of the Son to men, this supernatural love of God for His creatures, has so powerful an effect upon minds and hearts primarily because that mission was a revelation and continuation of the Trinitarian productions, and made men acquainted with the eternal relations existing among Father, Son, and Holy Spirit."
-Matthias Scheeben in The Mysteries of Christianity.