When Jacob died, Egypt mourned for seventy days (Genesis 50:3). Targum Pseudo-Jonathan explains why the Egyptians wept so hard for a foreign patriarch. They were not mourning only a man. They were mourning the reason the famine had ended.
"Come, let us lament over Jakob the Holy, whose righteousness turned away the famine from the land of Mizraim. For it had been decreed that there should be forty and two years of famine, but through the righteousness of Jakob forty years are withheld from Mizraim, and there came famine but for two years only."
This is a dazzling piece of Jewish theology. The Torah describes seven years of plenty and seven years of famine in Egypt (Genesis 41:30), and says the famine ended when Jacob and his family arrived in Goshen. The Targum reads the math differently: the heavenly decree was for forty-two years of famine. Jacob's mere presence — his zekhut, his accumulated righteousness — shortened it to two.
In Judaism, zekhut avot (the merit of the ancestors) is a live spiritual force. A single righteous person can tip the scales for millions. The Egyptians, the Targum says, understood this instinctively. They wept for seventy days because they knew whose righteousness had fed them. Grief is sometimes the clearest gratitude.