Essays / by Adam Smith.

  • Smith, Adam, 1723-1790.
Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Essays / by Adam Smith. Source: Wellcome Collection.

    473/482 (page 467)
    the pressure of the external body which excites them must necessarily suggest, not only some conception, but the most distinct conviction its own external and independent existence. ^ It maybe otherwise, perhaps, when those sensations are either of them excited by the temperature of the external air. In a calm ay when there is no wind, we scarcely perceive the external air as a solid body ; and the sensations of Heat and Cold, it rnay be thought, are then felt merely as affections of our own body, without any reference to any thing external. Several cases, however, may be conceived, m which it must be allowed, I imagine, that those sensations, even when . excited in this manner, must suggest some vague notion of some ex- ternal thing or substance which excites them. A new-born animal, which had the power of self-motion, and which felt its body, either agreeably or disagreeably, more heated or more cooled on the one side than on the other, would, I imagine, instinctively and antecedently to all observation and experience, endeavour to move towards the side m which it felt the agreeable, and to withdraw from that in which it felt the disagreeable sensation. But the very desire of motion supposes some notion or preconception of externality ; and the desire to move towards the side of the agreeable, or from that of the disagreeable sen- sation, supposes at least some vague notion of some external .thing or place which is the cause of those respective sensations. The degrees of Heat and Cold which are agreeable, it has been found from experience, are likewise healthful; and those which are disagree- able, unwholesome. The degree of their unwholesomeness, too, seems to be pretty much in proportion to that of their disagreeableness. If either of them is so disagreeable as to be painful, it is genera y destructive ; and, that, too, in a very short period of time. Those sen- sations appear to have been given us for the preservation of our own bodies. They necessarily excite the desire of changing our situation when it is unwholesome or destructive ; and when it is ^ allow us, or rather they entice us, to remain in it. But the desire o changing our situation necessarily supposes some idea of externa ity ; or of motion into a place different from that in which we actua y are , and even the desire of remaining in the same place supposes sonieidea of at least the possibility of changing. Those sensations could not well have answered the intention of Nature, had they not thus instinct- ively suggested some vague notion of external existence. That Sound, the object of the sense of Hearing, though perceived itself as in the ear, and nowhere but in the ear, may likewise, instinct- ively, and antecedently to all observation and experience, obscurely suggest some vague notion of some external substance or thing which excites it, I am much disposed to believe. I acknowledge, however, that I have not been able to recollect any one instance in which this sense seems so distinctly to produce this effect, as that of Seeing, that