In this week's portion, specific instructions are given to the Jewish army as to how to fight a war. Among them is one that you won't find in any other army manual, ancient or modern.

The Torah says that if you need materials to create a battering ram, do not use fruit trees; rather use tress that bear no fruit. This law applies even if it would be much more difficult to find the right trees.

The Sages then extrapolate to apply this principle more generally. In Jewish law, it is forbidden to waste a resource if one can find a way of accomplishing the task without any waste. All the more so, it is forbidden to waste a resource for no reason whatsoever. This law is called Bal Tashchit.

Recycling paper in order to protect rainforests is probably a good example of an attitude a Jew should have. Judaism would probably require a person to build a road around, rather than through, a woodland, even if it costs more to do so. Pollution of the environment would clearly be prohibited if there is a cleaner way to do the same thing, albeit at a higher price.

But why? Surely God's resources are infinite? If we destroy the rainforests, He could create them anew. If there is no ozone layer, He could protect us from the sun's rays in a different way. So what's the problem?

My mother often told me (as do most mothers, I believe) to finish my dinner because "there are children starving in Africa." From an early age I recognized this argument as spurious. If there was any conclusion to be made from starving African children, it would be to leave as much of my dinner as possible on the plate so that it could then be sent to feed those who really needed it.

But obviously mothers don't mean this literally - they are trying to point out that if others don't have something, it behooves us to appreciate the fact that we do.

The law of Bal Tashchit has a similar message - God has made us partners in His universe. While God could easily replenish the rainforests that we destroy, He will not do so - because He wants us to take responsibility for our own rainforests. He wants us to treat his world with respect and appreciation - and if we don't, it may well not be there for us. God has appointed us as caretakers of His universe. Only with the knowledge that we risk losing this gorgeous world God has made for us, will we be able to value it, take care of it, and truly enjoy it.