"And to Joseph were born two sons, before the years of famine came"
The subject of this final passage is the nature of "the days of evil." These are not the days of old age, Rabbi Yitzchak explains, but the "illumination of the left." Man should remain chaste in a bad time and not have children, since these "strange" children would descend from the left side - thus, Joseph had his sons before the famine struck. Neither should a man go forth into the marketplace during the days of evil, since the world is full of "satanic accusers" lying in wait for the unwary.
A man and woman's thoughts during sexual relations help determine the purity of their unborn child's soul. The purer our thoughts at the moment of conception, the finer the grade of soul that is drawn from the Upper Worlds. Because of social pressures and our Evil Inclination, purifying and controlling our thoughts is a formidable task. The cleansing attributes of the Hebrew letters in this passage help us to prevail over the world's negative influences, and to elevate our thoughts and desires. We draw Light to our children, which helps purify their souls.