He does not say, Where I shall be, but Where I am. For Christ was always there in that place whither He was about to return: He returned in such a way, as that He did not forsake us. Visibly and according to the flesh, He was upon earth; according to His invisible majesty, He was in heaven and earth. Nor again is it, Ye will not be able, but, Ye are not able to come: for they were not such at the time, as to be able. That this is not meant to drive men to despair, is shewn by His saying the very same thing to His disciples; Whither I go, ye cannot come; and by His explanation last of all to Peter, Whither I go, ye cannot follow Me now, but ye shall follow Me afterwards.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Tract. xxxi. 9