Descent for the Purpose of Ascent
No Pain No Gain
נס - Nes - Miracle
ניסיון - Nisayon - Trial
"All the affairs of the world, whether for the good or for the bad, are trials [nisyonos] for a man"… [Mesillat Yesharim* (Path of the Just) Rabbi Moshe Chaim Luzzatto]
When a person is destined to reach a level which is much higher than his present rung, it is necessary for him to undergo a descent first. [The Lubavitcher Rebbe]
Before a person experiences a miracle - נס - , he is given a trial - ניסיון. There is no ascent (aliyah) without a prior descent (yeridah). The lower the descent, the higher the potential ascent.
G-d tries the righteous, for knowing that the righteous will do His will, He desires to make them even more upright, and so He commands them to undertake a test, but He does not try the wicked, who would not obey.
Thus all trials in the Torah are for the good of the one being tried. [Nachmanidies, Commentary on the Torah; Genesis, p. 275; Chavel translation; ]
From here, we learn a number of important points. First, the purpose of a nisayon is not to reveal anything new to G-d, but to increase the spiritual reward of the person by bringing forth his or her latent greatness into actual deeds of righteousness.
Second, a person is only sent a nisayon that he or she has the potential to "pass," provided the person uses his free will properly.
Third (and this is implicit in the first point), the nisayon is intended for the good of the person—to elevate the person spiritually.
Nes can also be translated as "banner": The test is meant to "lift a banner" and reveal to the world, and to the person himself, the potential hidden within a human being.