(The Rebbe said, (In Sefer HaSeichas, Nun–Alef, page 73), “The way of the world, is one of hiding and darkness; and only afterwards, does there become revelation of the light.”)
Chassidus explains, that buried in darkness (the hiding of Hashem), are the highest revelations. Hidden in this limited physical world, is Atzmus (the essence of Hashem).
Atzmus is too high to be seen or revealed now; because if it were to be revealed, the world would disappear.
In order for Atzmus to be able to be contained in the finite world, the world has to have a very thick covering; which also hides the truth of Hashem's kingship.
Which is why this world is much more finite, that the upper worlds; where only a ray of the G-dly light, shines.
This is similar to someone who wants to look at the sun. In order to be able to see the sun, one has to put on sunglasses that filter out the strongest rays. The stronger the sunlight, the stronger the glasses have to be.
But the person does not see the total sun, only a filtered version.
The more physical or low the object is, the higher the light that is hidden in it.
As a result, evil in its source, actually contains in it a tremendous amount of G-dly light.
Esav being an example. Which is why as Chassidus explains, that most evil will be transformed into light, because Atzmus is hidden there.
This is why we see, that the order of creation was, that on the first day of creation G-d created Darkness, and then He created light. Esav was born before Yaakov. A tree first forms leaves first, and then the peel of the fruit; only at the end does the fruit itself form.
So too, Galus precedes Geulah. And as the Chassidic saying goes: After a fire one becomes rich.
Similarly, in a persons own life, it is the problems and obstacles that one may have, that one grows the most from, as a person.
We even also see how in darkness, is hidden a great deal of light. In many cases in Torah, it seemed that great Tzadikim sinned (darkness): Adam, Noach, Yehuda, Dovid Hamalech, etc. And Moshiach himself, (light), is descended from Ruth, a non-Jew (darkness).
The Oral Torah, (light), is based on Rabbi Akiva, who was a Ger (darkness). Hillel and Shami’s teachers were former non-Jews. And a Tzadik cannot stand in the place of a Baal Teshuvah (darkness), etc.
All because, in the greatest darkness, is hidden the greatest light.
In our generation, Atzmus, the infinite light, is gradually becoming revealed in a finite world. This is causing tremendous changes in the world.
The revelation of Moshiach contains the greatest light ever to be revealed in the history of the world. If comes too fast or in an open manner, the world will self-destruct.
It has to come as a process, in order for the world to acclimate to this new elevation. It has to come in a way of being hidden, then revealed, and then hidden again; in order for the world to adjust to each new revelation.
Through this process, the world has time to absorb the previous revelation, and be prepared for the next, higher revelation.
This back and forth process can be hastened, by utilizing the free-choice of the people, by preparing themselves and the world, so that this back and forth process can be quicker and easier.
Then great light that is entering the world will not blind the world, but rather it will illuminate the world.
And we will not need sunglasses to hide the light, but rather we will be able to look directly at the light and not blink.