"And now, if You will forgive their sin; and if not, erase me, please, from Your book which You have written." (Ex. 32:32)

How is this an example of Moses' humility, i.e. that his death should be an atonement for the great sin [of the Golden Calf]?

Rather, we must understand the nature of Moses' humility. It is easy to understand the humility of other people - which is the insignificance a person feels when compared to others. However, Moses knew the spiritual root and worth of each Jewish soul, as well as the greatness of his own soul, that included within it all the souls of Israel, as the Sages said: "One woman in Egypt gave birth to 600,000 at one time - this is Moses, our Teacher." (Zohar I:25a) How, then, could he possibly be humble?

A person who is not such a tzadik will also be inspired, but to a lesser degree….

It is written: "All Israel are responsible for one another" (Shavuot 39a; Sanhedrin 27b) - meaning, they are commingled with one another, for they all share a single root. Therefore, whenever a positive spirit from the source of goodness and holiness enters the world, it affects each and every Jew, according to his or her level. A tzadik will be greatly inspired to serve G‑d, with great holiness and longing. A person who is not such a tzadik will also be inspired, but to a lesser degree. Even a completely wicked person will be moved to thoughts of repentance, albeit only temporarily. Still, he is inspired a little, which may lead him to complete repentance.

The opposite is also true. When a spirit emanates from the side of evil, it also affects each person. The wicked will fall severely and commit a sin; whereas the tzadik will experience some [improper] thought, albeit momentarily.

Now, when we see that a wicked person has actually committed a sin, we have to ask, who is to blame? Perhaps the tzadik is to blame, because the improper thought also came to him, and had he immediately worked to nullify it at its root, the wicked person would not have sinned. On the other hand, perhaps the wicked person is to blame, because once he actually committed the sin, as soon as the thought entered his mind, the tzadik could no longer annul it.

Moses… would blame himself….

This is the essence of Moses' humility. Whenever he saw some bad trait in a Jew, he would blame himself, thinking that it was most likely his fault. This was his intention, when he said, "Erase me, please." That is, "I am the guilty one, not them!" But G‑d answered him, "Whoever has sinned against Me, I will erase from My book," meaning to say, "I know who is to blame!"

(Divrei Moshe, parashat Shemini)

There are two aspects of sin. The first is when the leader of the generation has a sinful thought, which causes the general populace to sin, G‑d forbid. The second is when the people sin, which can, at times, cause the leader of the generation to have sinful thoughts.

The difference between them is that in the first case, the leader cannot pray on behalf of the people, since the evil started with him. In the second case, the leader was compelled [by the people], and his prayers are still efficacious.

This is what Moses said: "And now, if You will forgive their sin" - that is, if You forgive them [on account of his prayers], then I will know that it is their sin, that they committed themselves. "And if not" - if You do not forgive them and my prayers are not accepted, then it is possible that my own thoughts are the cause. Therefore, "Erase me, please." Thus, the verse continues: "And the L-rd said to Moses, 'Whoever has sinned against Me, him will I erase from My book."

(Imrei Tzaddikim, in the name of the Kedushat Levi)

[Translated and annotated from Sefer Baal Shem Tov by Eliezer Shore]