Christiaan Huygens

It is inconceivable to me that a body should act upon another body without the intervention of some other thing.

The true cause of the refraction of light is the retardation of its motion in denser media.

Light is not a substance, but a motion propagated through an ethereal medium.

The undulations of light are not simple, but are composed of an infinite number of smaller undulations.

Nature does nothing in vain.

The more I examine the works of nature, the more I am amazed at the wisdom of their Author.

It is not enough to have a good mind; the main thing is to use it well.

Truth is the daughter of time, not of authority.

The world is my country, science is my religion.

I have often wondered that the most ingenious men have not been able to find out the cause of the refraction of light.

The velocity of light is finite, though very great.

The propagation of light is not instantaneous, but takes time.

The wave theory of light explains all the phenomena of reflection and refraction.

The ether is a subtle fluid that pervades all space.

The particles of the ether are perfectly elastic.

The motion of light is analogous to the motion of sound.

The colors of light are due to the different frequencies of the waves.

The polarization of light is a consequence of its wave nature.

The double refraction in Iceland spar can be explained by the wave theory of light.

The principle of Huygens states that every point on a wavefront can be considered as a source of secondary spherical wavelets.