is philosophical and scientific writings were by-paths of his
fertile mind. He was a theoretical rather than a practical scientist,
his contributions to science being in the nature of philosophical
reasonings rather than practical demonstrations. Had he been able
to withdraw from public life and devote himself to science alone, as
Descartes did, he would undoubtedly have proved himself equally great
as a practical worker. But during the time of his greatest activity in
philosophical fields, between the years 1690 and 1716, he was all the
time performing extraordinary active duties in entirely foreign fields.
His work may be regarded, perhaps, as doing for Germany in particular
what Bacon's did for England and the rest of the world in general.

Only a comparatively small part of his philosophical writings concern us
here. According to his theory of the ultimate elements of the universe,
the entire universe is composed of individual centres, or monads. To
these monads he ascribed numberless qualities by which every phase of
nature may be accounted. They were supposed by him to be percipient,
self-acting beings, not under arbitrary control of the deity, and
yet God himself was the original monad from which all the rest are
generated. With this conception as a basis, Leibnitz deduced his
doctrine of pre-established harmony, whereby the numerous independent
substances composing the world are made to form one universe. He
believed that by virtue of an inward energy monads develop themselves
spontaneously, each being independent of every other. In short, each
monad is a kind of deity in itself--a microcosm representing all the
great features of the macrocosm.

It would be impossible clearly to estimate the precise value of the
stimulative influence of these philosophers upon the scientific thought
of their time. There was one way, however, in which their influence was
made very tangible--namely, in the incentive they gave to the foundation
of scientific societies.

SCIENTIFIC SOCIETIES

At the present time, when the elements of time and distance are
practically eliminated in the propagation of news, and when cheap
printing has minimized the difficulties of publishing scientific
discoveries, it is difficult to understand the isolated position of
the scientific investigation of the ages that preceded steam and
electricity. Shut off from the world and completely out of touch with
fellow-laborers perhaps only a few miles awa