In maseches Sotah 21a there’s a dicussion about how much Torah and mitzvos protect a person, in relation to how long the z’chuyos, merits, of a woman brought for the Sotah waters will protect her. The Mishnah says that some z’chuyos will last for one year, two years, or three years. The Gemoro then tries to figure out what merits she could have that will last so long. It is explained that the z’chus of a mitzvah protects for a shorter period of time, because a mitzvah is compared to a candle which only burns for a short time; whereas the merits of learning Torah last longer, because Torah is compared to light itself. There’s a whole moshol there that describes the differences in terms of being out in the wild while it’s dark, it is however too long to go over in detail for this medium.
So, what we’ll want to understand is why does Torah have a more substantial effect in terms of protecting someone from problems? The Gemoro and Rashi say that this is because a mitzvah only lends protective power while someone is actively involved in it, whereas Torah grants protection even when not learning. The answer we can draw from Tosfos in particular is basically that a mitzvah grants protection from problems, but does not grant protection from the yetzer hara except for the time that we do the mitzvah.
Learning Torah has a longer lasting impact on the mind and soul than performing a mitzvah. The Ari says in Shaar Ruach HaKodesh that if someone makes tshuva and invests himself in constant study of Torah, then the marks on his head from his sins will be covered and eventually erased. Simple fulfillment of mitzvos may grant more light to the letters, but ultimately the tikkunim are done through learning Torah. Torah is the ultimate antidote for the yetzer hara, as it says in the Gemoro. Reb Pinchas Koritzer zy’a also said that when one makes tshuva, they should dedicate more time to learning Torah. At this time when we all need to make tshuva, which should be revealed and obvious due to our circumstances, I want to encourage everyone to add some extra amount of learning to your day. It doesn’t matter what it is, so long as it’s Torah and something somewhat significant. Through learning the yetzer hara is destroyed, and we can receive more Light from Hashem Yisborach, hence fulfilling the declaration that we must be a “Light unto the Nations.” Just as a candle (which is compared to mitzvos) has a light standing atop it (which is compared to Torah), so must we have the light of Torah standing upon us and the mitzvos we do in order to protect us from falling into the traps of gashmiyus and the yetzer hara.