20 INTRODUCTION. 
experienced. We trace to without the cause of that sensation, and thus 
acquire the idea of the object that has produced it. By a necessary law 
of our intelligence, all ideas of material objects are in time and space. 
The modifications experienced by the medullary masses leave impres- 
sions there which are reproduced, and thus recall to the mind images and 
ideas; this is memory—a corporeal faculty that varies greatly, according to 
the age and health of the animal. 
Similar ideas, or such as have been acquired at the same time, recall 
each other; this is the association of ideas. The order, extent, and quick- 
ness of this association constitute the perfection of memory. 
Every object presents itself to the memory with all its qualities or with 
all its accessary ideas. 
Intelligence has the power of separating these accessary ideas of objects, 
and of combining those that are alike in several different objects under a 
general idea; the object of which no where really exists, nor presents it- 
self per se—this is abstraction. 
Every sensation being more or less agreeable or disagreeable, experience 
and repeated essays soon shew what movements are required to procure the 
one and avoid the other; and with respect to this, the intelligence abstracts 
itself from the general rules to direct the will. 
An agreeable sensation being liable to consequences that are not so, and 
vice versa, the subsequent sensations become associated with the idea of 
the primitive one, and modify the general rules framed by intelligence— 
this is prudence. 
From the application of these rules to general ideas, result certain for- 
mule, which are afterwards easily adapted to particular cases—this is called 
reasoning. 
A lively remembrance of primitive and associated sensations, and of the 
impressions of pleasure or pain that belong to them, constitutes imagination. 
One privileged being, man, has the faculty of associating his general 
ideas with particular images more or less arbitrary, easily impressed upon 
the memory, and which serve to recall the general ideas they represent. 
These associated images are styled signs; their assemblage is a language. 
When the language is composed of images that relate to the sense of hear- 
ing, or of sounds, it is termed speech, and when relative to that of sight, 
hieroglyphics. Writing is a suite of images that relates to the sense of 
sight, by which we represent the elementary sounds, and by combining 
them, all the images relative to the sense of hearing of which speech is 
composed; it is therefore only a mediate representation of ideas. 
This faculty of representing general ideas by particular signs or images 
associated with them, enables us to retain distinctly, and to remember 
Without embarrassment, an immense number; and furnishes to the rea- 
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