481. Rabbi Yitzchak said that all those generations, which originated with AND CAME FROM Seth, were pious and righteous. Subsequently, as they spread and multiplied, they learned earthly skills of destruction with swords and spears, THAT IS, THEY LIVED UPON THEIR SWORD. This went on until Noah came. He improved the world for them and taught them to cultivate the land. When Noah first came, they did not sow and reap. THEY LIVED BY THEIR SWORDS and later, they depended on AGRICULTURE. THIS IS WHAT IS MEANT BY THE VERSE: "WHILE THE EARTH REMAINS..." (BERESHEET 8:22), BECAUSE THEN THE ART OF SOWING AND HARVESTING WAS PRACTICED.