1DEA0L0GY. 
have occurred to the mind. Previously to 
this, the conscious being may be said to 
possess the capacity to perceive and to de- 
duce relations ; and it seems of very little 
consequence whether we call this capacity 
innate or not. 
We are so constituted that most of our 
sensations give us either pleasure or pain ; 
and whenever these are vivid, we are put 
into a situation of mind respecting them 
called desire ; namely,, for the continuance 
or return of the pleasurable sensations, and 
for the cessation, or absence, of those that 
are painful. These desires, in their various 
modifications and combinations, are distin- 
guished by the general name of the passions. 
Whenever they are strong and urgent, they 
engage the mind so fully, that the ordinary 
association of ideas, and the regular pro- 
cesses of reason become obscured, inter- 
rupted, or suspended. A continuance of this 
state, as when the passions are exalted by 
disease, is called insanity ; and in all states 
of passion man is more or less insane. 
None of our sensations are simple, and 
consequently none of our ideas can be so. 
All sensations consist of parts, representing 
parts of the objects perceived, whether con- 
temporaneously or in succession; and we 
are also capable of receiving two or more 
sensations at the same time. Whether the 
difference between one sensation and ano- 
ther may arise merely from the relations of 
their own parts with respect to each other, or 
from any other causes, is not of importance 
to be discussed in this place ; but it is cer- 
tain that we are greatly interested in ob- 
serving these relations. Thus we take no- 
tice, that one thing is greater or less than 
another ; that in figure, position, duration, 
and other atfections, they are not the same; 
and that certain changes in inanimate, as 
well as in conscious beings, are without ex- 
ception followed by other changes, from 
which we are led to expect and to foretel 
events. This last class of observations 
establishes the doctrine of causes and 
effects; and a large part of our lives is 
employed in determining the order of these 
successions. 
Among numerous other inaccuracies 
which tend to mislead in the investigation 
of ideaology, a principal one is, that the 
term idea has been confounded with that of 
notion. Notions always grow out of the 
relations of ideas, and they always imply 
comparison. When the notion or thing as- 
serted, agrees with the ideas or . events, 
(which are ideas considered in succession) 
it constitutes truth ; if otherwise, it is false- 
hood. 
Our sensations in every case, without ex- 
ception, afford no more than a partial indi- 
cation of the nature ,of the objects which 
cause them. We cannot see the whole of 
an animal, but only one side, and that very 
imperfectly; so that the ordinary visible per- 
ception of a horse would be the same, 
whether its hair were long or short, its eyes 
imperfect or the contrary, & c. and the re- 
collection, or idea, of that individual horse 
would be still more imperfect, by the 
omission of particular variations or spots of 
colour, or other subordinate objects ; which, 
though they may have existed in the sensa- 
tion, have not remained in the memory. 
Thus it is, from the nature of things, that 
some part of the sensations will be ab- 
stracted, or left out in the idea : and if in 
reasoning upon that subject, namely, the 
horse, a comparison were to be instituted 
between that animal and a cow, the attributes 
they have in common would, in some cases, 
be alone attended to, and in others form the 
chief object of consideration. In this man- 
ner, arbitrarily, or rather from the necessity 
of the case, we constantly direct our in- 
quiries to abstract ideas, (which are more 
or less defective, when generally consider- 
ed) instead of attending to the individuals 
as we must always do in the sensations ; 
that is to say, when we observe and make 
experiments. And from these obvious 
truths we may see how it is that we acquire 
notions of genera, species, and individuals ; 
how the first elements of language are 
formed by abstraction ; how difficult it is 
to reason from sensations or experiments, 
by the use of ideas, which are their, neces- 
sarily imperfect, representatives ; and how 
easy it is for us to mislead ourselves, and 
others, by paralogism, in the use of general 
propositions, if we do not constantly adhere 
to the same degrees of abstraction, or if we 
do not, in all practical applications, again 
introduce the abstracted parts, which, 
though we may have rejected them (like 
numbers in algebra) for the facility of our 
mental process, must invariably be resumed 
whenever the theatre of nature or society 
is to be again entered. 
These are the principal outlines of the 
science which treats of ideas, or the mate- 
rials of our knowledge, and the conduct of 
mind, in the disposition and treatment of 
them. Most writers have treated this sub- 
