How are we to account for this restraint? Surely, in terms of the truth of which John’s Gospel in particular makes so much, the entire submission of the Son to the Father’s will. Part of the revealed mystery of the Godhead is that the three Persons stand in a fixed relation to each other. The Son appears in the Gospels not as an independent divine person, but as a dependent one, who thinks and acts only and wholly as the Father directs. “The Son can do nothing by himself”; “By myself I can do nothing” (John 5:19, 30). “I have come down from heaven not to do my will but to do the will of him who sent me” (John 6:38). “I do nothing on my own. .  . I always do what pleases him” (John 8:28-29). 

   It is the nature of the second person of the Trinity to acknowledge the authority and submit to the good pleasure of the first. That is why he declares himself to be the Son and the first person to be his Father. Though coequal with the Father in eternity, power and glory, it is natural to him to play the Son’s part and to find all his joy in doing his Father’s will, just as it is natural to the first person of the Trinity to plan and initiate the works of the Godhead and natural to the third person to proceed from the Father and the Son to do their joint bidding.

   Thus the obedience of the God-man to the Father while he was on earth was not a new relationship occasioned by the Incarnation, but the continuation in time of the eternal relationship between the Son and the Father in heaven. As in heaven, so on earth, the Son was utterly dependent upon the Father’s will. 

   But if this is so, all is explained. The God-man did not know independently, any more than he acted independently. Just as he did not do all that he could have done, because certain things were not his Father’s will (see Matthew 26:53-54), so he did not consciously know all that he might have known, but only what the Father willed him to know. His knowing, like the rest of his activity, was bounded by his Father’s will. And therefore the reason why he was ignorant of (for instance) the date of his return was not that he had given up the power to know all things at the Incarnation, but that the Father had not willed that he should have this particular piece of knowledge while on earth, prior to his passion. Calvin was surely right to comment on Mark 13:32 as follows: “Until he had fully discharged his (mediatorial) office, that information was not given to him which he received after his resurrection.” So Jesus’ limitation of knowledge is to be explained, not in terms of the mode of the Incarnation, but with reference to the will of the Father for the Son while on earth. And therefore we conclude that, just as there are some facts in the Gospels which contradict the kenosis theory, so there are no facts in the Gospels which are not best explained without it. 

Knowing God - J.I. Packer