No one can know the Father apart from God’s Word, that is, unless the Son reveals him, and no one can know the Son unless the Father so wills. Now the Son fulfills the Father’s good pleasure: the Father sends, the Son is sent, and he comes. The Father is beyond our sight and comprehension; but he is known by his Word, who tells us of him who surpasses all telling. In turn, the Father alone has knowledge of his Word. And the Lord has revealed both truths. Therefore, the Son reveals the knowledge of the Father by his revelation of himself. Knowledge of the Father consists in the self-revelation of the Son, for all is revealed through the Word.
From the treatise Against Heresies by Saint Irenaeus, bishop and martyr