=Sensation distinguished from Perception.=--It is impossible rigorously to _define_ a sensation; and in the actual life of consciousness sensations, popularly so called, and perceptions merge into each other by insensible degrees. All we can say is that _what we mean by sensations are_ FIRST _things in the way of consciousness_. They are the _immediate_ results upon consciousness of nerve-currents as they enter the brain, and before they have awakened any suggestions or associations with past experience. But it is obvious that _such immediate sensations can only be realized in the earliest days of life_. They are all but impossible to adults with memories and stores of associations acquired. Prior to all impressions on sense-organs, the brain is plunged in deep sleep and consciousness is practically non-existent. Even the first weeks after birth are passed in almost unbroken sleep by human infants. It takes a strong message from the sense-organs to break this slumber. In a new-born brain this gives rise to an absolutely pure sensation. But the experience leaves its 'unimaginable touch' on the matter of the convolutions, and the next impression which a sense-organ transmits produces a cerebral reaction in which the awakened vestige of the last impression plays its part. Another sort of feeling and a higher grade of cognition are the consequence. 'Ideas' _about_ the object mingle with the awareness of its mere sensible presence, we name it, class it, compare it, utter propositions concerning it, and the complication of the possible consciousness which an incoming current may arouse, goes on increasing to the end of life. In general, this higher consciousness about things is called Perception, the mere inarticulate feeling of their presence is Sensation, so far as we have it at all. To some degree we seem able to lapse into this inarticulate feeling at moments when our attention is entirely dispersed. =Sensations are cognitive.= A sensation is thus an abstraction seldom realized by itself; and the object which a sensation knows is an abstract object which cannot exist alone. _'Sensible qualities' are the objects of sensation._ The sensations of the eye are aware of the _colors_ of things, those of the ear are acquainted with their _sounds_; those of the skin feel their tangible _heaviness_, _sharpness_, _warmth_ or _coldness_, etc., etc. From all the organs of the body currents may come which reveal to us the quality of _pain_, and to a certain extent that of _pleasure_.