Gemara: "Hasket (literally, listen) and hear, Israel" (Devarim 27:9). Smash yourselves (kitetu) over words of Torah, as Reish Lakish said: How do we know that the words of Torah are preserved only in one who "kills himself" over it? It is as the pasuk says: "This is the Torah – should a person die in a tent" (Bamidbar 19:14).
Ein Ayah: When people join together to develop the world, the goal of the society is that people should be able to live in the land in an orderly, integrated, and normal manner. However, in order for the populace to live normally, it is necessary for some individuals to voluntarily dedicate themselves to efforts for the betterment of the society that far transcend the levels of normalcy.
We find this phenomenon in regard to a country’s soldiers. They sometimes have to go for long sleepless periods, on guard or in ambush for more hours than is healthy and normal. If they are noble people, they accept this burden upon themselves with love. In fact, they are happy with their work, as they know that only when they volunteer to put themselves in an abnormally difficult situation will they succeed in enabling their countrymen to live normal lives
The same is true of those special people to whom Hashem refers to as those who occupy themselves with Torah. They are the "brave soldiers on guard for their nation." They are the nation’s protective wall, protecting the nation as a whole. "I am a wall" – this is Torah; "and my breasts are like towers" – these are Torah scholars (Bava Batra 7b, based on Shir Hashirim 8:10).
If soldiers want to live their lives in normalcy and moderation, the nation is lost and no one will be able to live in tranquility. Then crime will increase and enemies will come to destroy it. For the same reason, Torah scholars need to be like soldiers who volunteer to work unusually hard in order to bring peace to the world and allow the light of Israel and the nation’s true life to continue properly. Therefore, they are to ignore the physical exhaustion that by necessity afflicts the majority of Torah scholars who toil in Torah study. Indeed, their physical body is expected to be smashed, and they are to be deprived of many of the pleasures of life and joys of the free-spirited. They are to push themselves physically, pressing themselves to the limit in order to enable full concentration on the intellectual requirements of scholarship, while pushing away feelings of pleasure that a broad life experience presents.
aIn this way, they can experience the great depth of abstract intellectual inquiry and moral contemplation, calculating how man can straighten his path and elevate himself above the desires that the evil inclination urges him to embrace. They do all of this without regard for that which they are missing in order to be able to teach others the good and straight path. The scholars are to kill the robust desire for enjoyment, which is fitting for the masses, but needs to be distant from the heart of those intellectuals who do the holy service of straightening the path of the nation.