To suggest, however, that an individual personality could be
discussed in vacuo would be to fall prey to what Whitehead described as the «fallacy of misplaced concreteness» (SMW 75).
Briefly considered, the mathematical aspects of the problem are as follows: If an aeroplane, moving
horizontally in vacuo, with a velocity of, say, 20 meters per second, should release a projectile at a point, A, Fig. 2, the projectile would take a parabolical path whose form and equation would be determined entirely by the height of the aeroplane and its speed with respect to the surface of the earth.