[331] "Unity of Worlds," p. 230.

[332] Tyndall.

[333] By the statical properties of matter we understand extension, limit, position, impenetrability, and inertia. We have no idea that there is a vis inertiæ in matter. Vis inertiæ is a forceless force, which is an absurdity. Inertness in matter is not a force, but the opposite of a force—a passivity which requires a force in order to change.

[334] Faraday, "Correlation and Conservation of Forces," p. 368.

[335] Clerk Maxwell, in Nature, vol. ii. p. 421; Herschel, "Familiar Lectures on Science," p. 467.

[336] Professor Norton, in the American Journal of Science and Arts, July, 1864, p. 64; Herschel, "Familiar Lectures on Science," p. 467; Dr. Carpenter, "Human Physiology," p. 542.

[337] Revue des Deux Mondes, 1867.

[338] Anaxagoras.

[339] Dr. Carpenter, in Nature, vol. vi. p. 312.

[340] Herschel, "Familiar Lectures on Science," p. 467.