PHILOSOPHY, MENTAL. 
I. OF THE SENSITIVE POWER. 
14. For a ronsideration of. the leading 
facts respecting this faculty, we beg our 
readers to consult in this place the follow- 
ing articles in their order; viz. Sensation, 
Sight, Smell, Sound or Hearing, Taste, 
and Touch. In the first will be found a 
brief account of the physical organ of sen- 
sation and motion. 
II. OF the retentive power, 
15. Respecting this faculty see the article 
Retention, where will also be found a few 
notices respecting ocular spectra. 
III. OF the associative power. 
16. This principle, if not the sole cause 
of all our mental phenomena, except the 
original production of sensorial changes and 
tendencies to them, has some effect in the 
origin and modification of all of them. It 
is owing to this important principle, that 
sensations become the signs of thoughts and 
feelings, by which means man becomes a 
social being ; that the whole mental furni- 
ture of perceptions, notions, aflFections, pas- 
sions, sentiments, emotions, &c. is formed 
from the simple relicts of sensation ; that 
man from mere sensation rises to intellect, 
that he becomes capable of reflection, of 
action. In short, whatever mental opera- 
tion we attend to, except at the very ear- 
liest period of mental culture, we find asso- 
ciation the cause of its production, or inti- 
mately concerned in it. 
17. The fact of the connection which ex- 
ists between many of our sensorial changes 
lias been long known ; but it has generally 
been referred to the memory. Mr. Locke 
appears to have been the first who employ- 
ed the principle of association to account for 
aberrations of judgment and feeling, and 
for customary connections of ideas ; but he 
does not seem to have been at all aware, 
that all our ideas, except those which are 
produced by mere repetitions of nneom- 
poimded sensible changes (i. e. ideas of sen- 
sation, or simple ideas, § 8) are in reality 
formed by the influence of the same prin- 
ciple ; that all our affections, and our mental 
pleasures and pains, are nothing more than 
the relicts of sensation variously combined 
by association. — It seems that Mr. Gay, a 
clergyman in the west of England, was the 
first who endeavoured to show the possibi- 
lity of deducing all our passions and affec- 
tions from association : his observations on 
this subject, however, as Dr, Priestley ob- 
serves, amount to little more than conjec- 
ture. These, however, led Dr. Hartley to 
direct his thoughts to the subject ; and by 
an union of talents in moral science, in na- 
ttiral philosophy, and in a professional know- 
ledge of the human frame, with a mind un- 
obscured by selfish tendencies, he was 
enabled to bring into one extensive system 
the progress of the mind from its first rudi- 
ments of sensation, through the maze of 
complex ideas and affections, to show how 
man rises from sensation to intellect. “ Af- 
ter giving the closest attention to the subject 
in a course of several years, it appeared to 
him very probable, not only that all our 
intellectual pleasures and pains, but that 
all the phenomena of memory, imagination, 
volition, reasoning, and every other mental 
affection and operation, are only different 
modes or cases of the association of ideas;” 
(more generally of sensorial changes ;) “ so 
that nothing is requisite to make any man 
whatever he is, but a sentient principle,witli 
this single property, which however admits 
of great variety, and the influence of such 
circumstances as he has actually been ex- 
posed to.” His great work was begun 
when he was about twenty-five years of 
age ; it was published in the beginning of 
1749, when lie was little more than forty- 
three years of age. He lived nine years 
after, but he left it without any change; and 
he does not appear to have written any 
additional paper on the subject. — As Dr. H. 
expected, his work remained for a consider- 
able time unnoticed. Tucker (A. Search) 
was obviously acquainted with it, and owed 
much to it ; but he seldom speaks of Hart- 
ley except respecting his hypothesis of vi- 
brations. Dr. Priestley had the merit of 
bringing Hartley’s system forward to the 
public notice ; and the celebrity which he 
had acquired among different classes of the 
philosophic world attracted the attention of 
thinking people to the doctrine of associa- 
tion. About thirty years after the publica- 
tion of the original work, he published an 
abridgment of it; in which he left out the 
deductions from the principal theory re- 
specting tlie rule of life, the truth of Chris- 
tianity, &c. and as much as he could of the 
hypothesis of vibrations. Since that time 
the system of Hartley has been rapidly 
gaining ground in South Britain ; and it is 
now, probably, pretty generally adopted by 
those who think closely on the subject. In 
North Britain, owing partly to theological 
and metaphysical prepossessions, still more 
perhaps to Dr. Priestley’s rough and unjus- 
