Baal HaSulam, “Introduction to The Study of the Ten Sefirot,” Item 121: Therefore, he says that if an individual performs one commandment, meaning after the repentance from fear, then one is short of only one commandment, and “He is happy for he has sentenced himself and the whole world to a scale of merit.” Thus, not only is he rewarded, through his repentance from love, with sentencing himself to a scale of merit, as the verse says, but he is even awarded sentencing the whole world to a scale of merit. …
Even after one has sentenced the whole world to a scale of merit, one should still not believe in himself until his dying day. Should he fail with a single transgression, he will immediately lose all his wonderful attainments, as it is written, “One sinner destroyeth much good.”
Observe this systematically. To the extent that a person takes it upon himself to be part of bestowal in longing to be similar to the Creator, he rises through the steps of the spiritual ladder and, thus, becomes an active, effective and determining part of the system.
According to the measure of his desire to be equivalent to the Creator, according to his Kelim (vessels), he discovers that he has become the most important part of the system, that he has become a representative of the Creator, as it is written, “a kingdom of priests and a holy nation,” in the aspect of Israel. Everyone depends on him and are under him.
Each one feels this attainment, and there is no contradiction because we are speaking about a system in which each soul has a Keter (crown), Malchut (kingdom), and Sefirot of its own that are located between bestowal and reception. Thus, when a person acquires the importance of the system in that he bestows to the entire environment in order to delight the Creator, then, time after time, he “sentences himself to a scale of merit.”
He does this in concealment and in stages through acts in solitude of bestowal. Then, he begins to feel the integral system and operates within it in completeness, in a comprehensive and general manner. This is how it goes.
With every opportunity, he sentences not only himself to a scale of merit, but the entire world. Accordingly, in the case of a downfall, he loses all of his “entries” in the system, all active bestowal of the system and “loses in favor of the many.”
Baal HaSulam describes this with the example of the King’s palace. It stands on the mountain that needs to be climbed, but, if we fall with a new egoistic desire, an uncorrected one that only now has become revealed, then we slide down the mountain and lose everything we attained.
Previously, this desire was “in order,” but now the evil that was hiding within is revealed that is much bigger than we previously knew and much more than the good we attained by working on ourselves. This big, evil desire throws us down in order to prepare the material for the ascension to the next, new level.
From the 4th part of the Daily Kabbalah Lesson3/27/12, “Introduction to the Study of the Ten Sefirot”