he gave a realistic attention to moral psychology. But he was incapable of
looking at the objects of any special enquiry without seeing them as
aspects or parts of one intelligible universe. He strove constantly after
system, and the instrument on which his effort relied was the speculative
reason. He embodied in an extreme form the spirit of his age. Nothing could
be less like the spirit of ours. To many people now alive metaphysics means
a body of wild and meaningless assertions resting on spurious argument. A
professor of metaphysics may nowadays be held to deal handsomely with the
duties of his chair if he is prepared to handle metaphysical statements at
all, though it be only for the purpose of getting rid of them, by showing
them up as confused forms of something else. A chair in metaphysical
philosophy becomes analogous to a chair in tropical diseases: what is
taught from it is not the propagation but the cure.

Confidence in metaphysical construction has ebbed and flowed through
philosophical history; periods of speculation have been followed by periods
of criticism. The tide will flow again, but it has not turned yet, and [8]
such metaphysicians as survive scarcely venture further than to argue a
case for the possibility of their art. It would be an embarrassing task to
open an approach to Leibnitian metaphysics from the present metaphysical
position, if there is a present position. If we want an agreed
starting-point, it will have to be historical.

The historical importance of Leibniz's ideas is anyhow unmistakable. If
metaphysical thinking is nonsensical, its empire over the human imagination
must still be confessed; if it is as chimerical a science as alchemy, it is
no less fertile in by-products of importance. And if we are to consider
Leibniz historically, we cannot do better than take up his _Theodicy_, for
two reasons. It was the only one of his main philosophical works to be
published in his lifetime, so that it was a principal means of his direct