Can you measure it? Can you express it in figures? Can you make a model of it? If not, your theory is apt to be based more upon imagination than upon knowledge.

Heavier-than-air flying machines are impossible.

Radio has no future." "X-rays are clearly a hoax". "The aeroplane is scientifically impossible.

We only know God in His works, but we are forced by science to admit and to believe with absolute confidence in a Directive Power-in an influence other than physical, or dynamical, or electrical forces.

There is nothing new to be discovered in physics now. All that remains is more and more precise measurement.

[Of the ether] it is no greater mystery at all events than the shoemakers' wax.

In science there is only physics; all the rest is stamp collecting.