work done, without saying anything about the doers of it. Meddling
with questions of merit and priority is a thorny business at the best
of times, and unless in case of necessity, altogether undesirable when
one is dealing with contemporaries. No such necessity lies upon me,
and I shall, therefore, mention no names of living men, lest,
perchance, I should incur the reproof which the Israelites, who
struggled with one another in the field, addressed to Moses--'Who made
thee a prince and a judge over us.'

[Sidenote: The aim of physical science]

Physical science is one and indivisible. Although, for practical
purposes, it is convenient to mark it out into the primary regions of
Physics, Chemistry, and Biology, and to subdivide these into
subordinate provinces, yet the method of investigation and the
ultimate object of the physical inquirer are everywhere the same.

[Sidenote: the discovery of the rational order of the universe]

The object is the discovery of the rational order which pervades the
universe, the method consists of observation and experiment (which is
observation under artificial conditions) for the determination of the
facts of nature, of inductive and deductive reasoning for the
discovery of their mutual relations and connection. The various
branches of physical science differ in the extent to which at any
given moment of their history, observation on the one hand, or
ratiocination on the other, is their more obvious feature, but in no
other way, and nothing can be more incorrect than the assumption one
sometimes meets with, that physics has one method, chemistry another,
and biology a third.