43 But perhaps the godless unbeliever meets the pious believer with the assertion that we cannot understand of the true God a confession of powerlessness, such as, Verily, verily, I say unto you, The Son can do nothing of Himself, but what He has seen the Father doing. If the twofold anger of the Jews had not demanded a twofold answer, it would indeed have been a confession of weakness, that the Son could do nothing of Himself, except what He had seen the Father doing. But Christ was answering in the same sentence the double charge of the Jews, who accused Him of violating the Sabbath, and of making Himself equal with God by calling God His Father. Do you think, then, that by fixing attention upon the form of His reply you can withdraw it for the substance? We have already treated of this passage in another book; yet as the exposition of the faith gains rather than loses by repetition, let us ponder once more on the words, since the occasion demands it of us.
Source: On the Trinity (New Advent)