On the contrary, such sadness is due to conceit.

For he does not know his place, and that is why he is distressed because he has not attained the level of a tzaddik, to whom such foolish thoughts surely do not occur.

For were he to recognize his station, that he is very far from the rank of tzaddik, and would that he be a Beinoni and not a rasha for even a single moment throughout his life [i.e., this is what he should be striving for at present, rather than vainly desiring to be a tzaddik], then surely, this is the due measure of the Beinonim and their task:

To subdue the evil impulse and the thought that rises from the heart to the mind, and to completely avert his mind from it, repulsing it [as it were] with both hands, as explained above [in chapter 12.

The Alter Rebbe explained there that the evil in the soul of the Beinoni remains vigorous; his task is to prevent it from expressing itself in thought, speech, and action. Thus, he has no control over the occurence of evil thoughts in his mind, but only over his acceptance or rejection of these thoughts].