LOGIC. 
rejected ideas, are the voluntai'y acts of the 
mind, adopted in order to facilitate the use- 
ful process of Comparison. Thus vve may 
abstract from bodies all ideas but those of 
structure, and divide them into organized 
and unorganized ; or we may take the or- 
ganized bodies, and call them animals and 
vegetables j or we may attend to their place 
of existence, and call them teirestrial, aqua- 
tic, volatile, and the like ; and many of our 
most useful propositions will, thus, in all 
our mental operations, continue equally ge- 
neral and abstracted. 
In the scientific arrangement of natural 
objects, philosophers have pursued the 
course of abstraction, until by rejecting all 
the ideas capable of affording the distinc- 
tive characters of individuals, they arrived 
at an hypothetical being called substance. 
Much has been written concerning it ; but 
it will perhaps be attended with the least 
obscurity to say, that it is supposed to be an 
independent existence which serves as the 
basis or suppoft to those properties which 
are perceived by our senses ; or, in the 
words of logicians, it is the subject of modes 
and accidents. 
The modes of substance are those disline. 
guishable objects of sense which might, if 
separate, produce simple ideas. Thus, soft- 
ness, fragrance, yellowness, and acidity, are 
among tlie modes which co-exist in the sub- 
ject or substance, lemon. Many distinctions 
are made in modes. They are called essen- 
tial or accidental, absolute or relative, &c. 
The moderns appear to use tlie words pro- 
perties of bodies, and powers and laws of 
nature, with much more distinctness than 
the earlier logicians did their modes and 
accidents. 
Words are intended to be the signs of 
things, but are very far from being so. If 
our ideas were adequate represeptations of 
the things which cause them, which they 
are not ; if they were not of necessity mu- 
tilated by abstraction, and there were not 
a continual exertion in language to emulate 
the rapidity of thought, then might words 
obtain the supposed resemblance. But the 
boasted extent and perspicuity of the intel- 
lect of man proceeds but a little beyond the 
signs and tones of those inferior animals 
who are supposed to have no power of con- 
versing. And even if we could vanquish 
the insuperable difficulties which impede 
our clear’mutual communication, what are 
the gi'ounds of our knowledge? they are 
very limited and often fallacious. 
Knowledge consists in the determination 
of those modes of surrounding beings which 
are taken to be permanent, and of those 
which ai'e observed to vary. The former are 
chiefly of the nature of quantity and posi- 
tion, and the latter seem resolvable into mo- 
tion. Mathematical science appears to com- 
prehend the whole of the first ; and the lat- 
ter, which embraces by far the greater part 
of what concerns our existence and well- 
being, is included in those histories of events 
upon which we establish our principles of 
cause and effect. Abstraction, or analysis, 
can give us very clear notions of the sub- 
jects of mathematics ; and in these alone it 
is that we find absolute proof or demonstra- 
tion. But in all the rest of our knowledge 
the facts are complex, obscure, and of un- 
certaine vidence ; and the principal, nay the 
only ground, of our reliance upon our doc- 
trines respecting them, is that our predic- 
tions are in many instances verified. 
Words being constructed and established 
by mere usage, are not only inadequate and 
contracted ia their use, but equivocal and 
synonimous ; that is to say, one word may 
be used to denote several distinct and dif- 
ferent things ; as when we speak of a beam 
of light, a beam of timber, or the beam of a 
pair of scales; or, on the contrary, as when 
we speak of an house, an habitation, or a 
residence. It must be admitted, however, 
that there are few synonymes in the practice 
of those who are masters of a language ; 
because few words are consecrated by usage 
to precisely the same meaning. 
Many acute and useful disquisitions have 
been written upon language and universal 
grammar. See Language. 
Since our idea of a thing must be com- 
posed or made np of all the simple ideas 
which that thing can produce by our per- 
ceptions, and this will for the most part be 
inadequate; the vvprd, denomination, or 
name of a thing, must be tlie sign of that 
idea, liable to such additional error as may 
arise from any improper use that may be 
made of it. And as by abstraction we ge- 
neralize our ideas and notions, and after- 
wards comprehend and compare them at 
our pleasure; so in the construction of lan- 
guage a like order is followed in words. 
Tims we may arrange things, from their 
similitude, under classes more or less ab- 
stracted as to their modes, calling these clas- 
ses by the names of genera and species. And 
in the names of things, we shall have not only 
to regard this arrangement ; but likewise the 
appropriation and correct use of the deno- 
mination itself If we had terms for all simple 
