any
obedient servants of an impulse which was at work long before him, and
will work long after him, that in science there is no falling back. In
respect to other things there may be times of darkness and times of light;
there may be risings, decadences, and revivals. In science there is only
progress. The path may not be always a straight line; there may be
swerving to this side and to that; ideas may seem to return again and
again to the same point of the intellectual compass; but it will always be
found that they have reached a higher level--they have moved, not in a
circle, but in a spiral. Moreover, science is not fashioned as is a house,
by putting brick to brick, that which is once put remaining as it was put,
to the end. The growth of science is that of a living being. As in the
embryo, phase follows phase, and each member or body puts on in succession
different appearances, though all the while the same member, so a
scientific conception of one age seems to differ from that of a following
age, though it is the same one in the process of being made; and as the
dim outlines of the early embryo become, as the being grows more distinct
and sharp, like a picture on a screen brought more and more into focus, so
the dim gropings and searchings of the men of science of old are by
repeated approximations wrought into the clear and exact conclusions of
later times.

The story of natural knowledge, of science, in the nineteenth century, as,
indeed, in preceding centuries, is, I repeat, a story of continued
progress. There is in it not so much as a hint of falling back, not even
of standing still. What is gained by scientific inquiry is gained forever;
it may be added to, it may seem to be covered up, but it can never be
taken away. Confident that the progress will go on, we cannot help peering
into the years to come, and straining our eyes to foresee what science
will become and what it will do as they roll on. While we do so, the
thought must come to us: Will all the increasing knowledge of nature
avail only to change the ways of man; will it have no effect on man
himself?

The material good which mankind has gained and is gaining through the
advance of science is so imposing as to be obvious to everyone, and the
praises of this aspect of science are to be found in the mouths of all.
Beyond all doubt, science has greatly lessened and has markedly narrowed
hardship and suffering; beyond all doubt, science has largely inc