ספר שיחות מוהר"ן אות - שב

Once he spoke with me about the matter of despising the well-known desire. And he said then: One who entertains thoughts of licentiousness [niaph] is a fool. For is it not the case that even a simple man — called a "baal habayis" [householder] — also does not want to be caught, Heaven forbid, in this matter. Even if he does not fear Heaven — even so he does not want to be caught in this matter because of shame and the opinion of others. And if so, how does one fool himself thinking that no one sees him? For Hashem Yisburach sees everything. And therefore it is complete foolishness for one who entertains such thoughts. And it is already explained that thought is in the hand of man to direct as he wishes, etc. — see in the printed books in many places about this.[477] And it will be pleasant for you forever if you are willing to receive them in truth.