Timaios (Continued) Regarding the causes of sensations such as smoothness and roughness, anyone who observes them should be able to explain them to others. Roughness arises from the mixture of hardness with unevenness, while smoothness is brought about by uniformity and density.

Timaios (Continued) Among the common functions of the entire body, the last remaining and greatest one is that which produces pleasure and pain. It involves receiving sensations throughout each part of the body, experiencing pain within them, followed by pleasure.

Timaios (Continued). Therefore, let us consider the causes of all actions that are perceived and those that are not, in the following way. Remembering what we previously distinguished as easily movable natures and less easily movable natures, we should pursue everything we seek to understand along this distinction, because everything is to be investigated according to this division.

Timaios (Continued): Things that are easily moved according to their nature, even if a very small force acts upon them, transmit that force in a circular manner. Each part produces the same effect on each other, and eventually reaches the thinking part, informing it of the power of what caused the initial action. In contrast, things that are difficult to move and remain stationary simply receive an action without tracing any kind of cycle, and do not affect anything nearby. Therefore, if the parts cannot transmit the action to another part, the initial action remains within those parts themselves. If this applies to the entire animal, it does not produce sensation in what receives the action.

Timaios (Continued) This applies to the parts of our body, such as bones and hair, which contain the most earth. On the other hand, what I mentioned before primarily relates to sight and hearing. This is because fire and air are the dominant forces within them.

Timaios (Continued) Regarding pleasure and pain, the following must be considered: Actions that occur against nature, forcefully and all at once, are painful. Actions that return to a natural state, occurring all at once, are pleasurable. Things that happen gradually and in small increments are not felt, and things that are their opposites act in the opposite way.

In contrast, everything that easily arises is extremely perceptible, but it does not relate to either pleasure or pain. For example, the function related to vision itself is like this. As mentioned earlier, vision naturally develops in us as a body connected to us every day.

In this case, even if the visual organ is cut, burned, or subjected to any other kind of action, it does not cause pain. Also, when returning to its original shape, there is no feeling of pleasure. On the other hand, regarding the actions that affect the visual organ, and also concerning the objects that the visual organ touches in some direction, the sensation is at its maximum and most clear. This is because there is absolutely no coercion involved in the separation and combination of vision.