Rabbi Eliezer Shenvald
Occasionally one of the 613 mitzvot, which is relevant to a specific situation, is actually a foundation and general principle in Judaism. This is the case with the mitzvah of the railing in our parsha, which relates to the obligation of homeowners to ensure the safety of their homes and install a railing on the roof (Devarim 22:8): "When you build a new house, make a railing for your roof, and do not bring blood upon your house, when someone will fall from it."
The Rambam (Laws of murderers, ch. 11, laws 1-3) learned that there are two mitzvot. A positive command: "a man must make a railing for his roof" and a prohibition to "leave his roof without a railing" which endangers life, by falling: "and do not bring blood upon your house." In this respect the Rambam determines that there is a general obligation, from the Torah, to remove every potentially dangerous hazard and protect the wellbeing of passers-by (law 4): "And regarding any life-threatening obstacle, there is a positive command to remove it and to beware of it and to be vigilant about this, as is written (Devarim 4:9): "Be alert, and guard your soul (life)." Similarly, the verdict of one who is negligent about removing hazards which he is responsible for and endangers passers-by is (ibid): "And if he didn't remove, and left the dangerous obstacles, he negated a positive commandment and transgressed "do not bring blood".
At first glance, it seems that the command is in the practical realm, reflecting a person's responsibility to remove hazards from his property. However, a closer look shows that this command encompasses a fundamental, wide-ranging issue, which is one of the foundations of the Torah, as expressed by Sefer HaChinuch (Mitzvah 546): "At the root of the mitzvah, notwithstanding that G-d closely watches over menand knows their deeds, and everything that happens to them, good or bad, is by His decree and command according to their merit or guilt…nevertheless a man must protect himself from the mishaps that happen in the world, because the Lord created His world and built it on the foundations of nature, and decreed that the fire burns and the water extinguishes the flame…and He favored man and breathed into him a life spirit with the intelligence to protect the body from every danger…and since G-d placed man's body under the laws of nature, as determined by His wisdom, since Man is a physical being, He commanded him to protect himself from accidents, since nature, which man lives under its rules, will act upon him if he doesn't protect himself from it."
The author of Sefer HaChinuch points to the apparent dialectic at the root of the command. On one hand, full faith in G-d, and in His ability to save man from every possible danger, even if he doesn't lift a finger. And on the other hand, the demand that man save himself and others from dangers reflects, apparently, a lack of faith in G-d's providence, as well as conduct as if man is the sole actor, and if he doesn't do by himself, nothing will happen.
The mitzvah of the railing reflects the Torah's verdict, that there is no lack of faith here, but to the contrary, we must recognize the fact that G-d allowed nature to act upon its rules, and to cause damage and danger. Therefore, the believer must be careful, and do his utmost to remove hazards. And not doing this runs contrary to the Torah's concept of faith, since it is "relying on a miracle." (ibid) "And therefore the Torah commands us to be careful in our homes and surroundings to prevent death by our wrongdoing, and not endanger lives by relying on miracles, and the Sages said (Torat Cohanim, Emor 8) "Whoever relies on a miracle - no miracle will be done for him!" On the other hand, the results do not depend solely on man's actions, and it's possible that circumstances beyond his control will disrupt his efforts. And here Divine Providence comes into play, which harnesses these circumstances as well to his success.
From this we see that the mitzvah of the railing reflects the fundamental approach to faith of the believer, in all areas of life and action. Success depends on a combination of complete faith in G-d's ability, and the obligation to not depend on a miracle and to make our maximum effort. To the contrary, the faith of one who doesn't make an effort is defective.
The author of Sefer HaChinuch also regards the "mitzvah of the railing" as the basis to a strategic approach to national security, as comes into play in the conduct of war according to the Torah. There also, in a Milchemet Mitzvah, G-d doesn't promise us that He will perform miracles. Therefore we must wage war in a natural way, according to military theory (ibid): "Also when Israel waged Mitzvah wars according to G-d, they conducted their wars in a natural way and armed themselves and did everything as if they relied exclusively on natural means. And this is the proper way to act (in a natural manner whenever possible, to prepare for war, etc.) and whoever doesn't deny the truth…will admit to this. (Ramban and Rebbanu Bechaii)
So we see that the strategic and military approach of the Torah, of belief and national security, is comprised of faith in G-d and maximal strategic organization. On one hand, we have to work according to all the principles and available information and using all the tools that progress offers. We have to make preparations, set goals, and operate at close and long ranges, just like any other properly functioning nation. However there are also forces beyond our control, which work against us, and they are liable to undermine our efforts. Therefore we put our hope and trust in G-d!
We don't count on miracles, but we believe that they happen!