Beginning with those at the outermost parts of the body, we find them located in the sense-organs, not only within the traditional five, but also within the muscles, tendons, joints, and internal organs of the body such as the heart, and digestive organs.

So far we have seen that the brain has the two functions of receiving impressions from the sense-organs and of sending out orders to the muscles.

The brain is the center where such transformations are made, being a sort of central switchboard which permits the sense-organs to come into communication with muscles.

The reason for this will be understood better if you keep in mind the fact, stated before, that nervous currents once started, whether from a sense-organ or from a brain-center, always tend to seek egress in movement.

It is probable that these products stimulate the sense-organs in the muscles and thus give some of the sensations of fatigue.

In fact, stimuli are continually playing upon the sense-organs and are arousing nervous currents which try to break over the boundaries of sleep and impress themselves upon the brain.

The first factor in the cognitive process is an impression on a sense-organ, which, occasioned by external motion, continues onward to the heart and from this center gives rise to a reaction.

Since I am just as ignorant how the sensation in my mind comes to pass as a sequel to the motion in the sense-organ; since, further, the body as an unconscious and non-rational being can effect nothing, it is neither I nor the body that causes the sensation.

If bodies transmitted to the sense-organs forms like themselves, these copies, which would evidently be corporeal, must, by their departure, diminish the mass of the body from which they came away, and also, because of their impenetrability, obstruct and interfere with one another, thus destroying the possibility of clear impressions.

While the finite mind perceives in the sensorium of the brain the images of objects which come to it from the senses, God has all things in himself, is immediately present in all, and cognizes them without sense-organs, the expanse of the universe forming his sensorium.

Fechner likens our individual persons on the earth unto so many sense-organs of the earth's soul.

Other creatures, in other planets, no doubt have other sense-organs to absorb other vibratory ranges.

But, these senses are not the sense-organs alone.