Note 27 — Chapter II · THE THEORY OF LOGICAL TYPES.
Reading edition
Cf. Poincaré, "Les mathématiques et la logique," Revue de Métaphysique et de Morale, Mai 1906, especially sections VII. and IX.; also Peano, Revista de Mathematica, Vol. VIII. No. 5 (1906), p. 149 ff.