I found a beautiful explanation of sefer Mishlei from the Vilna Gaon that sheds light on how the yetzer hara, the evil inclination, can trap us. In chapter 7 of Mishlei, Shlomo HaMelech says about the yetzer hara, that it first comes to us like this:
יג וְהֶחֱזִיקָה בּוֹ, וְנָשְׁקָה לּוֹ; הֵעֵזָה פָנֶיהָ, וַתֹּאמַר לוֹ. 13 So she caught him, and kissed him, and with an impudent face she said unto him:
יד זִבְחֵי שְׁלָמִים עָלָי; הַיּוֹם, שִׁלַּמְתִּי נְדָרָי. 14 'Sacrifices of peace-offerings were due from me; this day have I paid my vows.
The Vilna Goan asks what to peace offerings have to do with the yetzer hara? He says that with a peace offering its a mitzvah to eat the WHOLE thing, AND to be happy while you are eating it! Meaning, there is a real risk that through a mitzvah such as a peace offering, where there is a commandment to enjoy the physical world in a sense, there is a real risk that the yetzer hara will then take that experience and turn it to sins.
What's interesting is that I've noticed that I tend to fall with guarding my eyes after Shabbos, after I have enjoyed the physical world, when that enjoyment in a sense was a mitzvah! Here the Gra is teaching that even so, don't enjoy it so much to the point where the yetzer hara can then take that enjoyment of the physical world and isolate it from its spiritual root.
He says also there is a sense that when we do mitzvahs such as eating on Shabbos, we can think we 'paid our vows.' We did our part to enjoy the world in a spiritual way, and now we can take a "break" and enjoy it in a selfish way. Why do we think like that? Perhaps it is because we were wrong to think in the first place that it was ever ok, even on Shabbos, to enjoy the physical world as the physical world. Even on Shabbos, when we are allowed to indulge in pleasures that we normally aren't advised to enjoy during the week, it is still so important to keep in mind that this is still a spiritual form of serving Hashem, and that it is never recommended to us to enjoy the physical world for its own sake. Because once that happens, the yetzer hara says...
טו עַל-כֵּן, יָצָאתִי לִקְרָאתֶךָ; לְשַׁחֵר פָּנֶיךָ, וָאֶמְצָאֶךָּ. 15 Therefore came I forth to meet thee, to seek thy face, and I have found thee.
טז מַרְבַדִּים, רָבַדְתִּי עַרְשִׂי; חֲטֻבוֹת, אֵטוּן מִצְרָיִם. 16 I have decked my couch with coverlets, with striped cloths of the yarn of Egypt.
Here the Gra says that the the bedding represents the pleasures of this world that put us to sleep to our spiritual mission, and then the yarn of Egypt wraps us tighter in the pursuit of pleasure. This was all because the yetzer hara made us thing that when we were doing 'pleasure mitzvah's like eating on Shabbos, that it was ever ok, in the first place, to enjoy these pleasures as physical. No, we were only ever allowed to have those extra indulgences by seeing the physical pleasure as rooted in the spiritual world, and in that way to realize Gd's unity on all levels. But it was never ok, even on Shabbos, to enjoy the physical world for its own sake. Then the yetzer hara says...
יז נַפְתִּי מִשְׁכָּבִי-- מֹר אֲהָלִים, וְקִנָּמוֹן. 17 I have perfumed my bed with myrrh, aloes, and cinnamon.
Here he says 'perfuming the bed' means that the yetzer puts the person 'to sleep,' 'in bed,' asleep to his spiritual mission and to his post as a soldier fighting the yetzer hara. This is done through perfume, which has the same root as niuf, adultery. The yetzer hara is trying to steal us from our true spouse, our soul, by putting us into spiritual sleep.
Then it speaks about myrrh, aloes, and cinnamon. Here the Gra says that this represents the aspect that a person who does teshuva out of love is able to turn his sins into these beautiful fragrances. The yetzer hara knows that we want to grow and to teshuva, so it tells us that it is ok to sin by enjoying the world in a selfish way, because we can always do teshuva out of love and fix it. This is a big mistake, because we know that someone who says I will sin and then do teshuva will have a very difficult time doing teshuva. Not impossible, but much more difficult.
יח לְכָה נִרְוֶה דֹדִים, עַד-הַבֹּקֶר; נִתְעַלְּסָה, בָּאֳהָבִים. 18 Come, let us take our fill of love until the morning; let us solace ourselves with loves.
Again, the yetzer hara says let's enjoy sins until the morning, until the end of life when we pass away,; when at that time we can "solace ourselves with loves," i.e. that we can fix the sins at the end of life by doing teshuva from love. But we know, it is a big mistake to think that way "l'chatchila!"
I just found it interesting, helpful, and inspiring that I was having trouble consistently on motzei Shabbos, after Shabbos, when we were allowed to enjoy the physical world for spiritual purposes. Perhaps I have been enjoying the physical world for its own sake on Shabbos. Then the yetzer hara could get me to think that it was ok to do physical sins after Shabbos. But if we never enjoy the physical world for its own sake, even on Shabbos, we don't give the yetzer hara any chance to make us think that that is ever ok. So it could be that guarding the eyes, according to this, really begins with eating properly etc. with holiness..
