... the mathematician uses an indirect definition of congruence, making use of the fact that the axiom of parallels together with an additional condition can replace the definition of congruence.
The Philosophy of Space and Time (1928, tr. 1957)
... the mathematician uses an indirect definition of congruence, making use of the fact that the axiom of parallels together with an additional condition can replace the definition of congruence.
The Philosophy of Space and Time (1928, tr. 1957)
