historians have thought it possible that Napoleon saw it
and consulted it in his own expedition to Egypt. Their
evidence is, however, entirely internal. The scheme was
brought to the notice of Louis, and Leibniz was sum-
moned to Paris to explain it. This appears to have been its
only practical effect, for there is no evidence that Leibniz
actually saw Louis or any of his military advisers.

In his efforts towards the reunion of Christendom,
Leibniz was not merely trying to carry out his patron's
wishes; he genuinely desired to bring about tolerance
within the Christian community. His idea of toleration
was not a mutual forbearance, but an admission by Catho-
lics and Protestants of what he believed to be the truth,
that they shared a rational basis, and that this basis was
such as to make for good conduct and co-operation
among men. He thought of metaphysics as 'natural the-
ology', and this, he thought, should be as acceptable to
Catholic as to Protestant thinkers. He continually recom-
mended his metaphysical system on the ground that it was
compatible with the beliefs of all branches of the Christian
Church. Indeed, many of his metaphysical doctrines
developed from his attempt to find an account of material
substance which would be equally acceptable to Catholic
and Protestant theologians. By the end of his life, Leibniz
had moved away from a religion essentially connected
with ritual towards a natural religion, so much so that
when he was dying he refused to allow a minister of
religion to be summoned.

Although Leibniz's main purpose in going to Paris was
not fulfilled, it was for him a very fruitful visit. He stayed
there for four years, and though he did not meet the king,
he met Malebranche, Arnauld, Huygens, and Tschirn-
hausen, studied higher mathematics and Cartesianism, and
invented a calculating-machine. The machine of Leibniz
was an improvement upon that of Pascal in that it ex-

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