Cornelius a Lapide

What man knoweth the things of a man t Those in the inner recesses of his being, which are buried in his heart and mind, as, e.g, his thoughts, resolutions, and intentions, and the foundation of the character itself. Even so the things of God knoweth no man, but the Spirit of God , . The Holy Spirit knows them as well as Himself. For the Holy Spirit is internal to God, just as the spirit of a man is internal to him ; and as the spirit of a man is a sharer of his humanity, so the Spirit of God is a partaker of Godhead, and of the Divine omniscience and power. “The things of God* are those which are hidden in the mind of God — the thoughts, counsels and determinations of the Divine WilL After “knoweth no man, but the Spirit” must be understood, “and He to whom the Spirit has willed to reveal them, as to me and the other Apostles,” as was said in ver. 10. “No man, but the Spirit” does not exclude the Son. For since He is the Word, He knows the deep things of God. For in Divine things, when an exclusive or exceptive word is applied to one Person in respect of the Divine attributes, it does not exclude the other Divine Persons, but only all other essences from the Divine, i.e., it only excludes those whose nature differs from that of God. The meaning then is : No one knows the secret things of God, save the Spirit of God, and they who have the same nature with the Spirit, the same intellectual and cognitive powers, viz., the Father and the Son. These alone know the deep things of God