[86] See below, criticism of Erdmann, [§ 84.]
[87] See Prof. Land, in Mind, Vol. II.
[88] See concluding paragraph of Helmholtz's article in Mind, Vol. III.
[89] Cf. Veronese, Grundzüge der Geometrie (German translation), p. ix. Also pp. xxxiv, 304, and Note II. pp. 692–4.
[90] See [Chap. IV. § 197 ff.]
[91] Cf. the opinion of Bolyai, quoted by Erdmann, Axiome, p. 26; cf. also ib. p. 60.
[92] Die Axiome der Geometrie: Eine philosophische Untersuchung der Riemann-Helmholtz'schen Raumtheorie, Leipzig, 1877.
[93] On the influence of Mill, cf. Stallo, Concepts of Modern Physics, p. 216.
[94] This view seems to be derived, through Riemann, from Herbart. See Psych. als Wiss. ed. Hart. Vol. V. p. 262.
[95] The same irreducibility of space to mere magnitude is proved by Kant's hands and spherical triangles, in which a difference persists in spite of complete quantitative equality.