Hartshorne.] ^^^ [April 21, 



as vertically, the rays from the right side of the object crossing those from 

 the left side as they enter the eye, so that (as in a mirror) what is 

 right side in the object is left side in the retinal picture, and conversely; the 

 dithculty of the anatomical explanation referred to being at least doubled 

 by this ci^mplicaUon of revereal. 



It remains here for me to assert my adherence to the opinion, which is 

 generally' growing in favor with physiologists, that much the nearest ap- 

 proach to a solution of the problem of upright vision with inverted retinal 

 images must be expressed in terms essentially conforming to the 3d of the 

 hypotheses above briefly stated. The phraseology used in the passage 

 which I before quoted, making "an image projected outward" that which 

 (not the object) is seen, does not appear to me to be necessary, although it 

 has convenience in describing the analysis of some of the phenomena of 

 vision. 



That which it is especially my design to remark upon in this connection 

 is, the clear illustration furnished bj' our visual experience, and sustained 

 by that of our other senses, of the externality belonging to, and inherent in, 

 all sense-perceptions. Direction of sound is apprehended , even with only 

 one ear open to receive it ; the precise rationale of our recognition of the 

 direction of sounds not yet being agreed upon amongst physiologists. I 

 believe that it is obtained by the exquisite sensibility of the orifice, and 

 parts near it, of the external meatus of the ear; a sensibility intermediate 

 between auditory and tactile sense; a kind of gradation existing here, which, 

 there is reason to think, has many illustrations in the partially dtferentiated 

 sense-organs of lower animals. So, also, Ave judge, in case of touch, of the 

 direction from which anything comes, a ball, for instance, striking the hand, 

 by reversing, as it were, the central axis of predominance of the impres- 

 sions made; which is analogous to the ocular visual axes, whose corres- 

 pondence gives us single object-perception in sight. 



II. On Extuition as a New Term in Psychology. 



My reason for dwelling at some length upon the above points of statement 

 is, that I conceive it to be of consequence in psychology (which in regard 

 to sense-perception, especially, is inseparable from physiology), that a more 

 distinct apprehension should exist than has hitherto prevailed, as to 

 the essential, original and inherent, externality of the report made to our 

 consciousness by all our organs of sense, of the impressions made upon them. 

 In the but partially inductive study of psychology of past times, to which 

 the term "metaphysics" maybe, without disrespect, applied, the idea of the 

 Cartesian formula, "Cogito, ergo sum," has been accepted in too exclusive 

 or monopolizing a manner. This was, and is, a deduction occurring in the 

 self-consciousness of the mature philosopher. Could a child, a year old, 

 give its mental experience, so as to define its way of arriving at the knowl- 

 edge of the ego, of its own personal existence and identity, it would doubt- 

 less say, "Percipio, ergo stun." 



Not uncommonly, authors on psychology assert, in cflect, and sometimes 



