lain the meaning of sensation as a common quality of organism. What is the significance of pleasure and pain?
The question involves that of Life. Not to stray into foreign topics, it may broadly be said that as all change resolves itself into motion, and, as Helmholtz remarks, all science merges itself into mechanics, we should commence by asking what vital motions these sensations stand for or correspond to.
Every organism, and each of its parts, is the resultant of innumerable motions, a composition of forces. As such, each obeys the first law of motion, to wit, indefinite continuance of action until interfered with. This is a modification of Newton's "law of continuance," which, with the other primary laws of motion, must be taken as the foundation of biology as well as of astronomy.[11-1]
The diminution or dispersion of organic motion is expressed in physiological terms as waste; we are admonished of waste by pain; and thus admonished we supply the waste or avoid the