Augustine of Hippo — as excerpted in the Catena Aurea on John 3:32-36

“(Tr. xiv. c. 8) What is it, that God is true, except that God is true, and every man a liar? For no man can say what truth is, till he is enlightened by Him who cannot lie. God then is true, and Christ is God. Wouldest thou have proof? Hear His testimony, and thou wilt find it so. But if thou dost not yet understand God, thou hast not yet received His testimony. Christ then Himself is God the true, and God hath sent Him; God hath sent God, join both together; they are One God. For John saith, Whom God hath sent, to distinguish Christ from himself. What then, was not John himself sent by God? Yes; but mark what follows, For God giveth not the Spirit by measure unto Him. To men He giveth by measure, to His only Son He giveth not by measure. To one man is given by the Spirit the word of wisdom, to another the word of knowledge: one has one thing, another another; for measure implies a kind of division of gifts. But Christ did not receive by measure, though He gave by measure.”