INTRODUCTION. 53 



Ideas, between which some similarity exists, or 

 which have been acquired at the same period of 

 time, have a tendency to recall each other to the 

 mind. This tendency is termed the association of 

 ideas, and in its order, extent, and quickness does 

 the perfection of memory consist *. Each indivi- 

 dual object is presented to the memory with all its 

 peculiar qualities, or, to use more philosophic lan- 

 guage, with all its accessory ideas. 



The understanding possesses the power of sepa- 

 rating these accessory ideas from the objects of 

 thought, and of uniting together, under a general idea, 

 such qualities as are found to be alike in a diversity 

 of objects. The power of framing this general idea, 

 to which no corresponding type is to be found in 

 actual existence, is usually denominated abstraction. 



As every sensation is attended either with pleasure 

 or pain, in greater or less degrees, so experience 

 and repeated trials readily point out the means ne- 

 cessary to procure the one and avoid the other. 

 The understanding, then, forms general rules for the 

 direction, in this respect, of the ivill. 



As an agreeable sensation may be followed by 

 those which are unpleasing, and vice versa, we find 



* To enumerate all the sources of association would be difficult, 

 if not impossible. The earliest, and in uncultivated minds, the 

 most usual bond of union between the objects of thought is conti- 

 guity in time or place ; then follow resemblance and contrariety, 

 cause and effect, means and end, premises and conclusions, fyc. 

 To this associative principle some philosophers have referred all 

 the operations of the intellect, and, in fact, every thing in man, from 

 simple sensation upwards, .,♦ 



