498 On Memory. 
health recorded and treasured up within the secret tablet 
of the memory. 
She never told her love, » 
But let concealment, like a worm in the bud, 
Feed on her damask cheek ; she pined in thought, 
And with a green and yellow melancholy 
She sat like Patience on a monument, 
Smiling at grief. 
Dr. David Hartley, in his observations on man, his duty, 
his frame, and his expectations, agreeable to his mechanical 
theory of the human mind, defines memory to be that faculty 
by which traces of sensations and ideas recur, or are recalled 
in the same order as accurately, or nearly so, as they were re- 
presented. The rudiments of memory, he says, are laid in 
the perpetual recurrency of the same impressions, and thus 
he endeavours to account for the peculiar imperfections of 
the memory in children and aged persons, as well as for 
other facts pertaining to the exercise of this faculty. Those 
who adopt this theory enumerate among other phenomena 
of memory, the following :—Ideas of recollection are dis- 
tinguished from sensations chiefly by a difference in the 
vividness of impressions, so that when from disease, or any 
other cause, ideas become as vivid as sensations, they are 
mistaken for sensations, as in phrensy. Ideas of memory 
are distinguished from reveries, chiefly by the readiness and 
strength of the associations by which they are cemented 
together, and recollected ideas are also distinguished from 
reveries by their connection with known facts, and by 
various methods of reasoning. Memory, it is also said, 
depends entirely or chiefly on the state of the brain, hence 
diseases—concussion of the brain,—certain spirituous 
liquors, &c., impair it, but it generally returns with the 
renewal of health. 
Memory also differs at different ages, so that children 
soon learn and soon forget. Old people learn with difficulty, 
and remember best what they learned when young, and 
this, it is alleged, is agreeable to the theory of vibrations. 
Sensations attended with great pleasure or pain make a 
deep impression on the memory, which is probably owing 
to the strong vibrations which they excite. Sensible ideas 
gradually decay in the memory if not refreshed by new 
sensations. Voluntary recollection is performed by calling 
up associated ideas, which, by degrees introduce the idea 
in question. Some persons of weak judgment possess re- 
