No man’s span of perception is large enough, or his span of attention long enough, to surround the complete array of the uses of the word “right” unless this array be divided into classes. Such division will presently appear. And I think it can be shown that no matter how little in common some of the terms of this array seem, to a casual observer, to possess, when they are thus grouped into classes, they will be subtly linked together by adequate bonds. Let us then introduce: CLASS A _The Word “Right” as a Term that is Descriptive of Certain Mathematical Relationships and Physical Functions._[11] The original signification of our concept was _straight_, a word, be it noted, that is usually defined in the negative. (See Ex. 1, p. 76.) Why we have a negative definition for a word that seems to have a positive meaning, especially to mathematicians and draughtsmen, is not at first quite obvious. However, when this phenomenon is duly examined from the point of view of the mechanics of man’s locomotor apparatus, its secret is no longer hidden. All of the movements naturally produced by the appendages of the body are curvilinear: the arm being a lever, or radius vector, it always draws arcs in space or on paper; so does the hand as a whole, and so do the fingers. “Right” signifying _straight_, therefore, is defined negatively simply because straight lines are alien to the physics and mechanics of man’s original nature. Where, then, did man get the notion of straightness, and what has this first class of the uses of “right” to do with ethics? Man got the notion of straightness, we surmise, from such things as freely falling bodies, which give not only the idea of perpendicular, but also and at the same time the ideas of _direct_ and _immediately_; from the sunbeams which drew for him imaginary lines among the clouds and through the foliage of the forest; from his need of taking the shortest course across the fields in pursuit of wild animals for the supply of his larder; and from his reminiscent ponderings of the comparative merits of less and less curved and crooked arrows used in the chase. Moreover, man walks with the greatest safety and pursues his game with the greatest chances of success when his feet go without hesitation on a level or straight surface. Under these conditions he can attain his ends directly and immediately; as the saying is, “Things will then come out all _right_.” Consequently, even the straight line has ethical implications: the speed with which some actions are performed and the time required to cover the distance between man and his objective are very often the chief considerations in the attainment of a good or the avoidance of an evil thing. And this brings us by a very slight transition to Class B _“Right” as Descriptive of the Method (or Object) by Which the Desired End Can be Obtained._