Great was ignorant of the laws of motion, but knew very well what he meant by the measurement of time, and achieved his purpose by means of burning candles. Also no one in past ages justified the use of sand in hour-glasses by saying that some centuries later interesting laws of motion would be discovered which would give meaning to the statement that the sand was emptied from the bulbs in equal times. Uniformity in change is directly perceived, and it follows that mankind perceives in nature factors from which a theory of temporal congruence can be formed. The prevalent theory entirely fails to produce such factors."
Now let us turn to Professor Whitehead's view as to the meaning of 'position'. "Position is the quality which an abstractive element possesses in virtue of the moments in which it lies. The abstractive elements which lie in the instantaneous space of a given moment M are differentiated from each other by the various other moments which intersect M so as to contain various selections of these abstractive elements. It is this differentiation of the elements which constitutes their differentiation of position" (p. 92). Cannot one say that King Alfred was ignorant of intersecting families of durations, but knew very well what he meant by the position of the camp of the Danes? No one in past ages justified the use of methods of locating position by saying that some centuries later Professor Whitehead would discover intersecting families of duration and thus would give meaning to the statement that something has such and such a position in space. Why does not Professor Whitehead's theory compel the admission that there is no meaning to position except as certain assumptions as to intersecting durations give a meaning to it ? Is not such a statement historically false? Would not the natural view, on the contrary, be that position in space is directly perceived, and that it follows that mankind perceives in nature the factors from which a theory of position can be formed? Now mankind does not directly perceive the existence of different families of durations. No scientist, with all his training in powers of observation, has perceived such things. They are apparently signified by some observations made by scientists; but surely such things can hardly be the perceived factors in nature, which can give meaning to judgments of position.
If this criticism be a fair one, then it holds as well against Professor Whitehead's account of the meaning of perpendicularity, and perhaps against the way in which he takes the whole system which he
