certain Processes of the Human Understanding. 91 



the fact is, that the species of reasoning to which Mr. Stewart refers the judg- 

 ment has no existence in any case. The reasons not only never occur to the 

 understanding, but are not to be found by it, unless in the case of opticians, who 

 are themselves so little aided by their reasons, 'that they have long disputed as to 

 the means according to which vision is accompanied by a judgment of distance. 

 The theory here stated reduces this question to a very simple and obvious law — 

 the same long ago stated by Mr. Locke in his chapter on the Association of Ideas. 

 By habit we are enabled to understand our perceptions as the indications of ex- 

 ternal things ; the import of a habitual perception demands no reasons of any 

 kind ; it is become a part of it.* As the eye approaches or recedes, the appear- 

 ances of things uniformly alter ; and as the mind grows accustomed to these altera- 

 tions, it insensibly learns to translate them into the constant fact. Should any 

 occasion of doubt arise, the reasoning then steps in ; it is, however, seldom derived 

 from the laws of vision. When the judgment is not involved in the perception, 

 it Jbllows it. The artist whose business it is to imitate the appearances of things, 

 imposes on the perception, by producing the same indications in a different way ; 

 it is then that the judgment becomes antecedent, and that the law of the appear- 

 ances must be ascertained. In the common exercise of vision, distance is recog- 

 nized as every other object of sight which constant recurrence has made familiar. 

 By habit, the eye, ear, and all the senses acquire their proper scales of adaptation 

 — a law involved in every movement of the frame, in every living thing. 



There is another class of common facts, very curiously illustrative of the con- 

 clusion hei*e aimed at. I mean the numerous errors arising from our tendency 

 to combine, or from the habitual combinations of every individual. These, from 

 their nature, must be mostly peculiar, and even singular. Every one may recol- 

 lect some case in his own experience, and it is but a chance if any instance which 

 one person may offer will have come within the observation of another. An in- 

 stance may, however, be good for illustration. I recollect that once, on looking 

 at a picture which represented the interior of a cottage, with very unusual force and 

 truth, to have observed that the flame of the fire seemed to have the same quiver- 

 ing motion always accompanying the kind of flame represented. Now this could 



• The perception is itself a complex state of mind ; it is composed of certain sensations, and 

 certain judgments. 



m2 



