Ask the old man – Vayyechi
When Jacob was on his deathbed all his children wanted to know how the future was likely to turn out, and the dying man – as a prophet – was willing to tell them what he knew. At that moment, say the rabbis, the picture of the future was taken away from the patriarch.
It’s an allegory of life. We all yearn for knowledge of the future but God tells us it’s better that we shouldn’t know too much.
If we knew that the future would be evil, we would give up trying, because nothing would change the picture.
If we knew that things would turn out to be good, we would probably also give up trying because the picture would be good regardless of our efforts.