Bede : And when God saw that the earth was corrupt: for all flesh had corrupted its way. All flesh means all humans, according to the prophet's statement: "And all flesh shall see the salvation of God" (Luke 3:6). For neither birds nor quadrupeds had corrupted their way by sinning, just as they will not see the Salvation of our God, that is Christ, but all humans will see. — Commentary on Genesis (Hexaemeron) Ephrem the Syrian : Because the sons of Seth were going into the daughters of Cain, they turned away from their first wives whom they had previously taken. Then these wives, too, disdained their own continence and now, because of their husbands, quickly began to abandon their modesty, which up until that time they had preserved for their husbands' sake. It is because of this wantonness that assailed both the men and the women that Scripture says, "All flesh corrupted its path." — COMMENTARY ON Genesis 6.3.3