We should not [...] think of our efforts as wasted unless
they endure forever, or even for a very long time. We can make the world a
better place by causing there to be less pointless suffering in one
particular place, at one particular time, than there would otherwise have
been. As long as we do not thereby increase suffering at some other place or
time, or cause any other comparable loss of value, we will have had a
positive effect on the universe.