Note 4 at Lu 17:26: Jesus had just warned His disciples not to be deceived by false Christs, because His second coming would be visible to everyone (see note 2 at Lu 17:24). However, He began to explain here that until the very day of His coming (Mt 24:38 and Lu 17:27), the world will continue on its present course. People will not discern the signs of His coming just as the people during Noah's day didn't realize their impending judgment. This corresponds exactly with Jesus' prophecies about His coming being like the appearance of a thief in the night (Mt 24:43-44 and Lu 12:39-40). Jesus was emphasizing that the unbelievers will not recognize that He is coming until it is too late.