EXOD5 Part of the insidious nature of greed is the need not only to have it, but also to show off one's wealth and accomplishments to others. Jacob was well aware of this and that how appearances matter. Therefore, even though he and his family were not particularly in need of food, when there was a famine in the land of Israel and almost all of the surrounding families required food from Egypt, Jacob nevertheless instructed his sons to go to Egypt to obtain food. Why? The Talmud explains that Jacob was careful that his family should not appear to be showing off its wealth by not requiring Egyptian food to survive. Genesis 41:57-58, 42:1-2, Ta'anit 10b Unfortunately, it appears that this message did not carry over to the next few generations. Two generations later, it says that the new Egyptian King did not know Joseph, i.e., he ignored all the Joseph had done to save Egyptian society, and he began to enslave the Jews. What caused this sudden change of attitude toward Joseph and the Jewish people? The verse immediately prior to this one about the new king says that as the Jewish people multiplied greatly, they became exceedingly eminent "Bime'od, Meo'd," which is usually translated as "mighty." But we know from the Talmud and the explanation of the Shema cited above that this word also signifies "wealth." Thus, some interpret this verse to signify that the Jewish people showed off their wealth to the Egyptians (rather than keep it private), which is one of the symptoms of greed. It was for this reason that the Egyptian king and the Egyptian people turned against the Jews, despite everything that Joseph had done to save and lead the country. Berachot 54a