16. People say that fire is hot and bright. But think about it. When you stand a certain distance from the fire, you feel the sensation of warmth. As you approach the fire, that warmth gradually grows more intense and finally becomes pain. The pain is produced in the same way that the warmth was produced; the only difference is in how far you stand from the fire.

Now, people say that the fire has warmth in it, but no one would ever say that the fire has pain in it. But if warmth is produced in us the same way that pain is, then why should they be different? If there's no pain in the fire, then there's no warmth, either. What is actually in the fire is the power to produce both warmth and pain in us.

21. If you get one of your hands hot, and the other one cold, and put both hands into the same bucket of water, the water will feel cool to the first hand and warm to the second. If heat or cold were actually in the water, it could not be both warm and cold at the same time. Yet it is.

This can be explained in terms of the size, shape, and motion of tiny particles [atoms]. When you heat up one hand, its particles move faster, and when you cool down the other, its particles move more slowly. The particles in the water are moving at a rate in between those of the two hands. The hot hand (fast particles) perceives the motion of the particles in the water as slower, so it feels cool. The cold hand (slow particles) perceives the motion of the particles in the water as faster, so it feels warm.

Note that the same thing can't happen with shape: what feels like a sphere to one hand could never feel like a cube to the other hand.

25. Why are people so inclined to think that our sensations of color, etc. resemble qualities in the material objects themselves?

When we see how the sun causes a change in the color of wax or of pale skin, it never occurs to us to think that the wax is clear because there is clearness in the sun, or that the skin is red because there is a corresponding redness in the sun. Instead, we understand that what there is in the sun is the power to cause these changes in the wax and the skin.

We understand that this is only a power to create a change in color because we perceive both objects, i.e. the sun and the wax, or the sun and the skin. We can see that the sun doesn't have clearness or redness in it. We can perceive the dissimilarity between the sun's power and the change in color, the cause and the effect.

But it's different with material objects and our sensations. We can perceive the sensation of color, but we cannot perceive the tiny particles [photons or waves] that cause it. So we're unable to perceive the dissimilarity between our sensation and the particles that cause it. This leads us to think that there is a similarity between the object and our sensation, that the material object actually has color in it.