The Torah includes 613 mitzvot (divine commandments), ranging from the obvious ("Honor your father and your mother") to the esoteric ("Do not cook a kid in its mother's milk"), from the well-known ("Keep the Shabbat") to the obscure ("Do not muzzle an ox while it is threshing"). One of them — prohibition #57 by Maimonides' count — is Lo Tashchit, "Do not destroy," the prohibition to destroy or waste of any part of G‑d's creation.

Interestingly, the commandment not to destroy appears in the Torah as part of the laws of war. When laying siege to a city, the Torah instructs, do not cut down fruit trees to build siege towers from which to attack the city. Use regular trees. This injunction becomes the basis for the law that forbids all forms of wanton destruction or waste: "One who breaks a utensil, tears clothes, demolishes a building, stops a spring or disposes of food in a ruinous manner, transgresses the prohibition of Lo Tashchit" (Mishneh Torah and Codes).

War is basically a destructive act. So is cutting down a tree. Yet when the Torah wishes to tell us that it is forbidden to destroy, it gives us a case in which war is a necessity, and cutting down a tree is a necessity — and then tells us which trees not to cut down.

The Torah is in the details. We may be in a situation in which waging war is a necessity and a duty, but we are still obligated to distinguish between moral war waging and immoral war waging (indeed, the chapter containing the Lo Tashchit law includes numerous other rules and regulations on how to conduct a war). The fact that we're supposed to be cutting down trees right now does not absolve us from the duty to distinguish between non-wasteful cutting and wasteful cutting.

The same is true in the reverse. Also when we're doing something useful, we should constantly challenge ourselves: Am I using this the best way? Am I optimizing its — and my — potential? To achieve less than our capacity is like cutting down a fruit tree to build a siege tower.

The Chassidic masters take this a step further, applying this principle to all our resources — not just trees, buildings and food. Every thing that we have been given — time, energy, intelligence, experiences — has been given us for a purpose. Nothing is meaningless or superfluous in G‑d's world, and neither is any aspect or detail thereof.

A classic application of this principle is the Baal Shem Tov's teaching that "Everything that a person witnesses or hears about, should serve him as a lesson in how to serve his Creator." I'm walking down the street and I see something happen. Like everything in G‑d's world, the event serves a useful purpose. Often, the purpose and utility of this event may be obvious. But then there's also the fact that I saw it happen. So it's not enough to ask myself "Why did this happen?" — I must also ask, "Why did I see this happen?" The purpose of the event is served regardless of whether or not I am aware of its occurrence. So is this detail — the fact that I saw it — superfluous? If it does not teach me anything, then that aspect of the event has been wasted.

(See Pushcart Prophet, The Tightrope and A Million Little Cables for examples of this attitude in practice)

A common Jewish practice is to memorialize the dead by naming things, projects and institutions after them. There is nary a shul bench in Mineola or a park bench in Jerusalem, an ambulance in Brooklyn or a day school in Florida that does not bear an inscription attesting that it exists "In memory of..."

The Lubavitcher Rebbe explains this phenomenon as deriving from the Lo Tashchit principle — from the Jewish idea of usefulness.

For the soul of the departed, death is not a loss or a waste. On the contrary: it is an advance to a purer state of existence, an ascent to a loftier and more spiritual rung in its journey towards fulfillment.

But what about us, those left behind in the physical world? What about our experience of the event? To us, the death of a loved one is a loss, a void, an awful, terrible waste.

That is why it is so important to translate our feelings of loss and futility into the impetus to create something, to do something useful. This assures that not only is the soul of the departed elevated in the cosmic sense, but that no detail of the event of death — including the responses it provokes in the lives of those who remain within a physical world and perspective — should ever, G‑d forbid, be a waste.