45 But the Apostle does not neglect to say with what manner of confession we should bear witness of God. O the depth of the riches both of the wisdom and of the knowledge of God! How unsearchable are His judgments, and His ways past tracing out! For who has known the mind of the Lord? Or who has been His counsellor? Or who has first given to Him, and it shall be recompensed unto him? For of Him, and through Him, and in Him are all things. To Him be the glory for ever and ever. No earthly mind can define God, no understanding can penetrate with its perception to sound the depth of His wisdom.
His judgments defy the searching scrutiny of His creatures: the trackless paths of His knowledge baffle the zeal of all pursuers. His ways are plunged in the depths of incomprehensibility: nothing can be fathomed or traced to the end in the things of God. No one has ever been taught to know His mind, no one besides Himself ever permitted to share His counsel. But all this applies to us men only, and not to Him, through Whom are all things, the Angel of mighty Counsel, Who said, No one knows the Son save the Father: neither does any one know the Father save the Son, and him to whom the Son has willed to reveal Him. It is to curb our own feeble intellect, when it strains itself to fathom the depth of the divine nature with its descriptions and definitions, that we must re-echo the language of the Apostle's exclamation, lest we should attempt by rash conjecture to snatch from God more than He has been pleased to reveal to us.
Source: On the Trinity (New Advent)