between a philosopher and a maniac. It was all the difference
between a living tree and a dead one, between an inert mass and a
growing organism. The transition of knowledge from the dead to the
living form must, in any complete review of the subject, be looked
upon as the really great event of modern times. Before this event
the intellect was bound down by a scholasticism which regarded
knowledge as a rounded whole, the parts of which were written in
books and carried in the minds of learned men. The student was
taught from the beginning of his work to look upon authority as
the foundation of his beliefs. The older the authority the greater
the weight it carried. So effective was this teaching that it
seems never to have occurred to individual men that they had all
the opportunities ever enjoyed by Aristotle of discovering truth,
with the added advantage of all his knowledge to begin with.
Advanced as was the development of formal logic, that practical
logic was wanting which could see that the last of a series of
authorities, every one of which rested on those which preceded it,
could never form a surer foundation for any doctrine than that
supplied by its original propounder.

The result of this view of knowledge was that, although during the
fifteen centuries following the death of the geometer of Syracuse
great universities were founded at which generations of professors
expounded all the learning of their time, neither professor nor
student ever suspected what latent possibilities of good were
concealed in the most familiar operations of Nature. Every one
felt the wind blow, saw water boil, and heard the thunder crash,
but never thought of investigating the forces here at play. Up to
the middle of the fifteenth century the most acute observer could
scarcely have seen the dawn of a new era.