There are a host of sources that demonstrate how critical shmiras einaiym is for succeeding in avodas Hashem. But perhaps we should first begin with a brief anecdote that demonstrates the extent to which our gedolim understood the importance of guarding their eyes.
Anyone observing the scene could not help but laugh.
Here was a stately old man, with his eyes tightly shut, surrounded by a gaggle of giggling children. They were directing the old man. “Make a right turn!” “No!” “Stop!” “Watch out for the pole!” The game continued until the man reached his destination. He smiled at the children and entered the house.
Who was this playful old man?
It was none other than the Chazon Ish!
This story was recounted by R’ Shimon Schwab. He explained that the Chazon Ish was once asked to attend a certain event, and he realized en route that he would have to pass a place where there were improper sights, so he asked these unsuspecting youngsters to play this game with him.
What a lesson in the importance of shmiras einayim!
Let us now enumerate but a few of the many sources that highlight the importance of shmiras einayim:
“Anyone who gazes at married women weakens his yetzer tov“ (Beis Yosef, Even HaEzer 21, citing Rabbeinu Yonah).
“Be very careful about improper thoughts and sights because they cause terrible damage to all spiritual pursuits” (Yaaros Devash 1:165).
“Just as Torah protects an individual from tumah, so (conversely) does tumah damage Torah and contaminate it. Anyone who stumbles in kedushah related issues weakens his Torah and dulls his mind” (Ha’amek Davar, Vayikra 18:30).
“Whatever you learn in the kollel by day you will lose on the commute back and forth unless you are careful where you look” (the Steipler Gaon to a young kollel man, cited in L’Shichno Tidrishu).
And on the positive side:
“Through overcoming his desires, one brings great Kiddush Hashem ... and thereby merits incredible siyata d’Shmaya in all matters, be it in studying Torah or improving one’s character, and even in matters pertaining to this world” (Karienah D’Igartah 15 [2]).
“One who is careful in inyanei kedushah merits to be a ‘king’ (Zohar) ... Since talmidei chachaim are referred to as ‘kings,’ this means that one who preserves his kedushah merits to disseminate Torah and kedushah to other Jews” (see Taharas HaKodesh, Maalas Notrei HaYesod 28).
In this vein, R’ Nosson Wachtfogel, Mashgiach of Beth Midrash Govoha in Lakewood, once related this to his students:
“I want to share something I have never told anyone. How did I, of all people, merit to become the Mashgiach of the yeshivah? I have nothing! Other people also wondered about this. Why did R’ Aharon choose me to be Mashgiach? There were many better candidates than myself. What did he see in me? Clearly, no great wisdom or insight! The secret is this: I merited this position because I guarded my eyes. No one knows about this. People know nothing, but I worked on guarding my eyes, and everything I merited was due to this. My rebbetzin’s students would come to our house every Shabbos and I had to speak to them at length. I never looked at them, and they never realized it (the Mashgiach demonstrated how he did this) ...’’ (Kuntres Leket Reshimos).