Earlier this year I was reading a series of questions, mostly about Scripture, answered by St. Maximos the Confessor. It’s known in Latin as Quaestiones et dubia, but the passage I’m interested in seems to come from an appendix/supplement to the work. In any case, I’m translating it from Cerf’s edition, Questions et difficultés, pp. 175-176. Here it is:
Qu. I, 67: How should we understand the ignorance of the Son on the final things (cf. Mt 24:36, Mk 13:32)?
There are two kinds of ignorance. The first kind is blamable, the other kind isn’t. The blamable kind, which depends on us, is ignorance with respect to virtue and piety. And the other kind, which doesn’t depend on us, is ignorance with respect to whatever we want to know but don’t, such as the things coming in the future. But if the holy prophets, by the grace of God, knew the distant events that are not up to us, how much more then did the Son of God, and through him his humanity, know all things (knowing them, of course, not by his human nature but by his human nature’s union with the Word of God). In the same way that iron that has been heated red-hot has all the properties of fire – it is bright and burning – being still not fire by nature, but iron by nature, so the humanity of the Lord, in that it was united to the Word, knew all things and showed attributes proper to God. And he is said to be ignorant according to his human nature. [Translation slightly adapted using the translation from Greek in Robert Moloney, Knowledge of Christ (London: Continuum, 1999), p. 46.]
EDIT (May 2017): I have removed the rest of this post (which was mostly conjecture) because I have since discovered more information on the patristic understanding of Christ’s knowledge. Please see here. It seems like the quote above from St. Maximus, which denies ignorance of Christ in his humanity, summarizes the patristic consensus from at least the 600-700s onward. However, note that the exact practical ‘consequences’ of the presence of the divine knowledge in Christ’s humanity were understood differently by different theologians (see, for example, Aquinas’s solution about Christ’s need for knowledge from his senses to express his divine knowledge).