Henry Adams Quote

... by action on man all known force may be measured. Indeed, few men of science measured force in any other way. After once admitting that a straight line was the shortest distance between two points, no serious mathematician cared to deny anything that suited his convenience, and rejected no symbol, proved or unproveable, that helped him to accomplish work. The symbol was force, as a compass-needle or a triangle was force.

The Education of Henry Adams (1907)