[151] Also called the axiom of congruence. I have taken congruence to be the definition of spatial equality by superposition, and shall therefore generally speak of the axiom as Free Mobility.
[152] For the sense in which these figures are to be regarded as material, see criticism of Helmholtz, [Chapter II. §§ 69 ff.]
[153] Op. cit. p. 60.
[154] The view of Helmholtz and Erdmann, that mechanical experience suffices here, though geometrical experience fails us, has been discussed above, [Chapter II. §§ 73], [82.]
[157] Contrast Delbœuf, L'ancienne et les nouvelles géométries, II. Rev. Phil. 1894, Vol. xxxvii. p. 354.
[158] Prolegomena, § 13. See Vaihinger's Commentar, II. pp. 518–532 esp. pp. 521–2. The above was Kant's whole purpose in 1768, but only part of his purpose in the Prolegomena, where the intuitive nature of space was also to be proved.
[159] On the subject of time measurement, cf. Bosanquet's Logic, Vol. i. pp. 178–183. Since time, in the above account, is measured by motion, its measurement presupposes that of spatial magnitudes.
[160] Cf. Stumpf. Ursprung der Raumvorstellung, p. 68.