By the “east” and “west,” He signifies the whole world, throughout which the Church should be. In the same way as He said below, “Hereafter shall ye see the Son of Man coming in the clouds, of heaven,” [Matt 26:64] so now He likens His coming to lightning, which uses to flash out of the clouds. When then the authority of the Church is set up clear and manifest throughout the whole world, He suitably warns His disciples that they should not believe schismatics and heretics. Each schism and heresy holds its own place, either occupying some important position in the earth, or ensnaring men’s curiosity in obscure and remote conventicles.
“Lo, here is Christ, or lo, there,” refers to some district or province of the earth; “the secret chambers,” or “the desert,” signify the obscure and lurking conventicles of heretics.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Quaest. Ev., i, 38