This number must include many issues, bearing the heads of different British sovereigns and various devices and inscriptions; but all shillings approximate to one standard in shape, size, and weight, and agree in consisting of the metallic substance known as silver.
Now if we compare ideas (here taken in the strictly subjective sense) with coins, both being characteristic products of human intelligence, though ideas are also integral parts of intelligence, what we should usually call one idea is comparable, not to one coin, but to a set of coins of one kind or value. The instances of the idea, analogous to actual coins of a given stamp, are the notions which momentarily appear in human consciousness simultaneously with some term which calls the idea to the mind of some person. In this sense the same idea may occur or may have occurred to the minds of all normal persons, living and dead, while in each mind it may recur an indefinite number of times.
Thus, in respect of its logical extension or actual occurrences to human consciousness, any given idea may be distinguished as either cultural or personal, and any personal idea as either habitual or presented.
Cultural ideas are those conveyed by literature of all sorts, and are such that each presumably occurs and recurs to a multitude of human minds, many particular cultural ideas having been thus familiar to men throughout the ages of historical civilization.
Personal ideas are those which occur or recur to individual consciousness.
Habitual ideas are those which have (to use an obvious metaphor) taken root in the individual mind, and which recur to personal consciousness according as practical occasion, deliberate reflection, or some casual association may determine.
A presented idea, which may also be termed a notion, is one which is in actual course of passing in the mind, or, in other words, one which forms a particular 'process-content of consciousness.'
