St. Augustine, City of God, 11.2.
God “established and founded this faith, that man might find a way to man’s God through God made man. For this is ‘the Mediator between God and man: the man Christ Jesus’. For it is as man that He is the Mediator and the Way. If there is a way between one who strives and that towards which he strives, there is hope of his reaching his goal; but if there is no way, or if he is ignorant of it, how does it help him to know what the goal is? The only way that is wholly defended against all error is when one and the same person is at once God and man: God our goal, man our way.”