DEUT1153 Build a fence (parapet) on your roof. Included in the mitzvah is that we must repair any wall, fence or other standing object (e.g. a tree) that is no longer sturdy and threatens to fall. Our Sages enacted many laws and prohibitions in order to prevent accidents, property damage and other harm, for as intelligent beings, it is inappropriate to leave ourselves open to danger and injury. A person not only must be aware of objects and situations that present a potential danger to him; he also must take care that neither he nor his property endangers others. Key concept: Divine Providence reaches down to every individual, which means that Hashem is intimately aware of every person’s every deed, and whatever happens to us, good or bad, is a result of His decree, based on our merits and sins. Nevertheless, we are not exempt from watching out for “natural” occurrences. Hashem created the world in such a manner that fire burns, water extinguishes fire, a large boulder that falls on a person’s head will crush his brain, and someone who falls him a great height will die. The Creator, blessed be He, blows into a person's nostrils a living soul that knows to protect from harm the body that houses it. The Torah, as well, explicitly commands us to beware of natural events that might hurt or kill us, and the Torah forbids us to place ourselves in dangerous situations and rely upon miracles to save us. We are not allowed to trust that the Almighty violate His laws of nature in order to save us from our own negligence. [True, some people are so saintly and cling so tightly to Hashem, they are masters over nature. Avraham Avinu, for example, was thrown into a blazing furnace and emerged unharmed. Clearly, however, most of us, because of our sins, are not on such a high level, so nature poses real threats to our safety, and we cannot rely on miracles to save us from them.]