Almost all the advantages, which man possesses above the inferior animals, arise from his power of acting in combination with his fellows; and of accomplishing, by the united efforts of numbers, what could {129} not be accomplished by the detached efforts of individuals. Without the power of communicating to one another their sensations and ideas, this co-operation would be impossible. The importance, therefore, of the invention of signs, or marks, by which alone that communication can be effected, is obvious. Among sensible objects, those alone which are addressed to the senses of seeing and hearing have sufficient precision and variety to be adapted to this end. The language of Action, as it has been called, that is, certain gesticulations and motions, has very generally, especially among rude people, whose spoken language is scanty, been found in use to indicate certain states, generally complicated states, of mind. But, for precision, variety, and rapidity, the flexibility of the voice presented such obvious advantages, not to mention that visible signs must be altogether useless in the dark, that sounds, among all the varieties of our species, have been assumed as the principal medium by which their sensations and ideas were made known to one another. There can be little doubt that, of the two uses of marks, Communicating our thoughts, and Recording them, the advantage of the first would be the earliest felt; and that signs for Communicating would be long invented, before any person would see the advantage of Recording his thoughts. After the use of signs for Communication had become familiar, it would not fail, in time, to appear that signs might be employed for Recordation also; and that, from this use of them, the highest advantages might be derived. In respect to those advantages, the following particulars are to be observed. {130} 1. We cannot recall any idea, or train of ideas, at will. Thoughts come into the mind unbidden. If they did not come unbidden, they must have been in the mind before they came into it; which is a contradiction. You cannot bid a thought come into the mind, without knowing that which you bid; but to know a thought is to have the thought: the knowledge of the thought, and the thought's being in the mind, are not two things but one and the same thing, under different names. If we cannot recall at pleasure a single idea, we are not less unable to recall a train. Every person knows how evanescent his thoughts are, and how impossible it is for him to begin at the beginning of a past train, if it is not a train of the individual objects familiar to his senses, and go on to the end, neither leaving out any of the items which composed it, nor allowing any which did not belong to it, to enter in.