Each individual fact, taken by itself, can indeed arouse our curiosity or our astonishment, or be useful to us in its practical applications.

What we see is the solution to a computational problem, our brains compute the most likely causes from the photon absorptions within our eyes.

Black is real sensation, even if it is produced by entire absence of light. The sensation of black is distinctly different from the lack of all sensations.

Just as a physicist has to examine the telescope and galvanometer with which he is working; has to get a clear conception of what he can attain with them, and how they may deceive him; so, too, it seemed to me necessary to investigate likewise the capabilities of our power of thought.

The originator of a new concept...finds, as a rule, that it is much more difficult to find out why other people do not understand him, than it was to discover the new truth.

When young Galileo, then a student at Pisa, noticed one day during divine service a chandelier swinging backwards and forwards, and convinced himself, by counting his pulse, that the duration of the oscillations was independent of the arc through which it moved, who could know that this discovery would eventually put it in our power, by means of the pendulum, to attain an accuracy in the measurement of time till then deemed impossible, and would enable the storm-tossed seaman in the most distant oceans to determine in what degree of longitude he was sailing?

A metaphysical conclusion is either a false conclusion or a concealed experimental conclusion.