In the world, these is often a big difference between theory and practice.
Things which should work properly in theory often fail in practice because of
unseen complications. This is true of many things, including both machines
and ideas. In older times, for example, many people devised machines which
were supposed to be self-propelling, and thus could run forever. It was only
later that people learned that energy cannot be created or destroyed, but
only transferred, and thus a "perpetual-motion device" was impossible.
Similarly, many great political leaders have thought of systems which would
create a better government, but every attempted political system thus far has
shown flaws, many of which were not foreseen.
  People who spend much of their time speaking of perfection, theorizing
about how things should be, are often called "idealists". This term is often
used in a negative connotation, implying that these idealists are not
down-to-earth and don't realize that "The world just doesn't work that way".
These people seem to be of the opinion that it's very nice to talk about how
things should be and how people should live, but in reality, you sometimes
have to make compromises with those ideals. The general feeling is "You just
can't live that way".
  My question is: "Why not?" Why should you have to compromise principles,
just because they're hard to keep? Sure, hanging on to them may make things
harder, but it's sure not going to be any better if you let go of them.
  Many people have the goal of being rich. But do they give up this idea,
simply because they are not rich right now and see no way of becoming so?
Hardly. They continue trying, working at it, thinking up new ways at becoming
rich. These ideas might not work, but people sure are not going to get rich
by giving up that goal.
  In the same way, just because the world is not made a perfect place by the
thinking of these idealists, that's no reason to make concessions. Idealists
are people who have a clear idea of how they want things to be, and they want
to see their vision realized, even though it may be difficult. This, to my
mind, is how people should be: The idealist is trying to make the world a
better place, while the person who decides to "go with the flow" has a
meaningless life, because they are conforming to the world, instead of
letting the world conform to them.
  Of course, people can't spend all their time just thinking; They must act
as well. High-minded people need to take action to see their ideals realized.
But since the "ideal" world is the "perfect" world, if people want things to
get better, then idealism is the way to go.