Regardless of all its pride, it must put up with toning down its bold claims commanding a priori assent, and must expect approbation for the universal validity of its propositions from the indulgence of the observers who, as witnesses, would surely not refuse to admit that what the geometrician sets forth as principles they too had always perceived to be thus, and would consequently grant that, even though it is indeed not necessary, one may yet continue to expect it to be thus.