Chapter III: ENERGY AND FORCE. Page 96

The term Force is by many authors used as equivalent to Energy, rather than as a distinct term for the amount of Energy. Force is thus used by Sir W. R. Groves. "The term Force, although used in very different senses by different authors, in its limited sense may be defined as that which produces or resists motion." ... "I use the term Force ... as meaning that active principle inseparable from matter which is supposed to induce its various changes." ... "All we know or see is the effect; we do not see Force--we see motion or moving matter."--_The Correlation of Physical Forces_, sixth edition, by the Hon. Sir W. R. Grove, pp. 10, 11.