Parshat Vayechi

Bereishit 49:1
And Jacob called his sons and said, “Come together that I may tell you what is to befall you in days to come.”
THAT I MAY TELL YOU: He wished to reveal to them the end of Israel’s exile but the Shechinah departed from him and he began to speak of other things.
Berakhot 34b
All the prophets prophesied only regarding the days of the Messiah, but regarding the World to Come, “No eye has seen it, God, aside from You.” (Isaiah 64:3) 
Rabbi Adin Steinsaltz
…the curtain that stands before Jacob,  is neither a result of sin nor a result of a defect in his sons or in himself. … when Jacob must speak of a phenomenon that is beyond is audience’s range of perception, it turns out that he lacks vocabulary to express himself. … there are some fundamental gulfs that are impossible to bridge.
Reality allows us to relate only to things that belong to the plane of being, experience, and action in which we exist. … [The World to Come] is a promise of things that we have seen and cannot hope to comprehend.
[There are also ordinary things that are difficult to communicate — such as what is in our hearts. We must use words to express our feelings and then the other person must translate those words into what is in their heart.]
There are skills that are not included in any course of study, yet everyone must learn them. Sometimes a person must dedicate much of his life to these skills. One of these skills is the ability to develop a keen sense for things that cannot be said. … In matters of faith, anything that can be studied or articulated in words is irrelevant and unhelpful. … What remains is the responsibility to learn to sense, to intuit, that something exists beyond our comprehension, beyond the range of man’s ordinary perception, and to learn to relate to it.
Our task, in any form of faith, is to develop an awareness that beyond the place that I know lies a place that I do not know. If we can accomplish this task, we can truly claim to have experienced even that which “no eye has seen.”
Rabbi Yehudah Leib, Alter of Ger
This is why Rashi says that “Jacob sought to reveal the end, but it was hidden from him.” He wanted to make clear that exile is just a matter of hiding, and that the power within comes only from God. But had this been revealed, there would have been no exile at all, so “it was hidden.”
I believe my grandfather quoted the Rabbi of Przysucha as wondering why Jacob wanted to reveal the end. His answer was that when the end is known, exile is made easier. 
…by faith Jews have that there is no power other than God, even if it is all hidden, even if you can’t see it with your eyes, you can still come to see truth within faith. Jacob our Father just wanted there to be no mistake about this, that it all be obvious, but that goal eluded him. You need to struggle to find truth.