at the turning-point
of modern thought.

Galileo's work, his experiments with falling bodies and the revelations
of his telescope, carried the strategic lines of Greek science across
the frontiers of a New World, and Newton laid down the lines of
permanent occupation and organized the conquest. Organization, the
formation of a network of lines connected as a whole, and giving access
to different parts of the world of experience, is perhaps the best image
of the growth of science in the mind of mankind. It will be seen that it
does not imply any exhaustion of the field, nor any identification of
all knowledge with exact or systematic knowledge. The process is rather
one of gradual penetration, the linking up and extension of the area of
knowledge by well-defined and connected methods of thought. No
all-embracing plan thought out beforehand by the first founders of
science, or any of their successors, can be applied systematically to
the whole range of our experience. It has not been so in the past; still
less does it seem possible in the future. For the most part the
discoverer works on steadily in his own plot, occupying the nearest
places first, and observing here and there that one of his lines runs
into some one else's. Every now and then a greater and more
comprehensive mind appears, able to treat several systems as one whole,
to survey a larger area and extend that empire of the mind which, as
Bacon tells us, is nobler than any other.

Of such conquerors Newton was the greatest we have yet known, because he
brought together into one system more and further-reaching lines of
communication than any one else. He unified the forms of measurement
which had previously been treated as the separate subjects of geometry,
astronomy, and the newly-born science of dynamics. Celestial mechanics
embraces all three, and is a fresh and decisive proof of the commanding
influence of the heavenly bodies on human life and thought. Not by a
horoscope, but by continued and systematic thought, humanity was
unravelling its nature and destiny in the stars as well as in itself.
These are the two approaches to perfect knowledge which are converging
more and more closely in our own time. Newton's work was the longest
step yet taken on the mechanical side, and we must complete our notice
of it by the briefest possible reference to the later workers on the
same line, before turning to the sciences of life which began their more
systematic ev