Sentence:  Hereby , the external <WSD>object</WSD> viewed by the eyes remains the thing that is seen , not the retinal image , the purpose of which would be to achieve perceptive cooperation by stirring sympathetic impulses in the other sensory centers , motor tensions , associated word symbols , and consciousness . 
Meaning of the word marked with <WSD> tags:  a tangible and visible entity; an entity that can cast a shadow