All potential energy exists in the ether. It may vibrate, and it may…

The waves of light are not anything mechanical or material, but are something electrical and magnetic—they are, in fact, electrical disturbances periodic in space and time, and travelling with a known and tremendous speed through the ether …

A body can only act immediately on what it is in contact with; it must be by the action of contiguous particles—that is, practically, through a continuous medium, that force can be transmitted across space.

The oldest and best known function for an ether is the conveyance of light, and hence the name "luminiferous" was applied to it, though at the present day many functions are known, and more will almost certainly be discovered.

What properties are essential to a medium capable of transmitting wave motion? Roughly, we may say two: elasticity and inertia.

Motion and force are our primary objects of experience and consciousness; and in terms of them all other less familiar occurrences may conceivably be studied and grasped.

Life must be considered sui generis; it is not a form of energy, nor can it be expressed in terms of something else.