In Zettel, Wittgenstein asks the reader to consider two philosophers, one an idealist, the other a realist, who are raising their children to share their philosophical beliefs. An idealist holds that physical objects only exist in so far as they are perceived; talk of unperceived physical objects is merely a means to making predictions about future observations. The realist holds that physical objects exist independently of our capacity to perceive them. Wittgenstein suggests that both philosophers will teach their children how to use vocabulary about physical objects in exactly the same way, except, perhaps, that one child will be taught to say, "Physical objects exist independently of our perceptions," and the other will be taught to deny this. If this is the only difference between the two children, says Wittgenstein, "Won't the difference be one only of battle-cry?" (Wittgenstein, 1967, 74). (..) His claim in this case is that those sentences which philosophers take to express substantive statements about realism and idealism play no role whatsoever in our lives. The metaphysical sentences have no use, and so there is nothing to be understood -- they are strings of words without a meaning. Wittgenstein's hope is that once we see that, in a given metaphysical dispute, both sides are divided by nothing more than their different battle cries, both parties will realize that there is nothing to fight about and so give up fighting.