the real
life of science can be fully felt and communicated by the man who has
not himself been taught by direct communion with Nature. We may, it is
true, have good and instructive lectures from men of ability, the
whole of whose knowledge is second-hand, just as we may have good and
instructive sermons from intellectually able and unregenerate men. But
for that power of science, which corresponds to what the Puritan
fathers would call experimental religion in the heart, you must ascend
to the original investigator.

To keep society as regards science in healthy play, three classes of
workers are necessary: Firstly, the investigator of natural truth,
whose vocation it is to pursue that truth, and extend the field of
discovery for the truth's own sake and without reference to practical
ends. Secondly, the teacher of natural truth, whose vocation it is to
give public diffusion to the knowledge already won by the discoverer.
Thirdly, the applier of natural truth, whose vocation it is to make
scientific knowledge available for the needs, comforts, and luxuries
of civilized life. These three classes ought to co-exist and interact.
Now, the popular notion of science, both in this country and in
England, often relates not to science strictly so called, but to the
applications of science. Such applications, especially on this
continent, are so astounding--they spread themselves so largely and
umbrageously before the public eye--that they often shut out from view
those workers who are engaged in the quieter and profounder business
of original investigation.

Take the electric telegraph as an example, which has been repeatedly
forced upon my attention of late. I am not here to attenuate in the
slightest degree the services of those who, in England and America,
have given the telegraph a form so wonderfully fitted for public use.
They earned a great reward, and they have received it. But I should be
untrue to you and to myself if I failed to tell you that, however high
in particular respects their claims and qualities may be, your
practical men did not discover the electric telegraph. The discovery
of the electric telegraph implies the discovery of electricity itself,
and the development of its laws and phenomena. Such discoveries are
not made by practical men, and they never will be made by them,
because their minds are beset by ideas which, though of the highest
value from one point of view, are not those which stimulate the