Answer: Now it is impossible. Only in the end will all of the separate events be collected and lead to the collective correction, called “Rav Paalim u-Mekabtziel”. After accumulating all of our vessels, they will simultaneously unite in a unified state, and then this action will be accomplished. It will sum up all of the generations of the many billions of people and will collect all of their affairs into one. This is when the time of the full correction will arrive, which will unite all of us into one desire, perfect, and filled with the Light of Infinity.
Until then, we are forbidden to perceive the past because we would not be able to endure all of the things we had experienced. We do have the fortitude needed for that, in other words the screen (Masach). Today we would not be able to justify the states we have experienced.
That is why we tend to oblivion. We switch off from time to time. This periodic “blackout” is actually no more than switching between two moments, between the day yesterday and the day today, between the past and present lives, until finally they will be all gathered into one.
From the Introductory Lecture Series 1/17/12, “Course to Be A Man, Human Development”