systematic manner. As discoveries were gathered in, either one by
one, or in groups resulting from the continued prosecution of some
uniform course of inquiry, the truths which were successively brought
into store cohered and became agglomerated according to their individual
affinities. Without any intentional classification, the facts classed
themselves. They became associated in the mind, according to their
general and obvious resemblances; and the aggregates thus formed, having
to be frequently spoken of as aggregates, came to be denoted by a common
name. Any body of truths which had thus acquired a collective
denomination, was called a _science_. It was long before this fortuitous
classification was felt not to be sufficiently precise. It was in a more
advanced stage of the progress of knowledge that mankind became sensible
of the advantage of ascertaining whether the facts which they had thus
grouped together were distinguished from all other facts by any common
properties, and what these were. The first attempts to answer this
question were commonly very unskilful, and the consequent definitions
extremely imperfect.

And, in truth, there is scarcely any investigation in the whole body of
a science requiring so high a degree of analysis and abstraction, as the
inquiry, what the science itself is; in other words, what are the
properties common to all the truths composing it, and distinguishing
them from all other truths. Many persons, accordingly, who are
profoundly conversant with the details of a science, would be very much
at a loss to supply such a definition of the science itself as should
not be liable to well-grounded logical objections. From this remark, we
cannot except the authors of elementary scientific treatises. The
definitions which those works furnish of the sciences, for the most part
either do not fit them--some being too wide, some too narrow--or do not
go deep enough into them, but define a science by its accidents, not its
essentials; by some one of its properties which may, indeed, serve the
purpose of a distinguishing mark, but which is of too little importance
to have ever of itself led mankind to give the science a name and rank
as a separate object of study.

The definition of a science must, indeed, be placed among that class of
truths which Dugald Stewart had in view, when he observed that the first
principles of all sciences belong to the philosophy of the human mind.
The observation i