Hilary of Poitiers
Catena Aurea · Johannesevangelium 3
For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved. He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
(vi. de Trin. c. 40) If it were only a creature given up for the sake of a creature, such a poor and insignificant loss were no great evidence of love. They must be precious things which prove our love, great things must evidence its greatness. God, in love to the world, gave His Son, not an adopted Son, but His own, even His Only Begotten. Here is proper Sonship, birth, truth: no creation, no adoption, no lie: here is the test of love and charity, that God sent His own and only begotten Son to save the world.