John Calvin Commentary 1 Thessalonians 5:2

"For yourselves know perfectly that the day of the Lord so cometh as a thief in the night." — 1 Thessalonians 5:2 (ASV)

You know perfectly. He places exact knowledge in contrast with an anxious desire for investigation. But what is it that he says the Thessalonians know accurately? It is, that the day of Christ will come suddenly and unexpectedly, so as to take unbelievers by surprise, as a thief does those who are asleep. This, however, is opposed to evident signs, which might portend from afar his coming to the world. Hence it would be foolish to wish to determine the time precisely from omens or portents.