Theophylact of Ohrid
Catena Aurea · Lukasevangelium 21
And when these things begin to come to pass, then look up, and lift up your heads; for your redemption draweth nigh. And he spake to them a parable; Behold the fig tree, and all the trees; When they now shoot forth, ye see and know of your own selves that summer is now nigh at hand. So likewise ye, when ye see these things come to pass, know ye that the kingdom of God is nigh at hand. Verily I say unto you, This generation shall not pass away, till all be fulfilled. Heaven and earth shall pass away: but my words shall not pass away.
For because He had foretold that there should be commotions, and wars, and changes, both of the elements and in other things, lest any one might suspect that Christianity itself also would perish, He adds, Heaven and earth shall pass away, but my words shall not pass away: as if He said, Though all things should be shaken, yet shall my faith fail not. Whereby He implies that He sets the Church beforethe whole creation. The creation shall suffer change, but the Church of the faithful and the words of the Gospel shall abide for ever.