Logicism by the end of the 19th century was a philosophical doctrine whose time had come, and it is Gottlob Frege to whom we owe its arrival. "Often," Frege once wrote, "it is only after immense intellectual effort, which may have continued over centuries, that humanity at last succeeds in achieving knowledge of a concept in its pure form, in stripping off the irrelevant accretions which veil it from the eyes of the mind" ([Fd], p. xix). Prior to Frege, logicism was just such a concept whose pure form was obscured by irrelevant accretions; and in his life's work it was Frege who first presented this concept to humanity in its pure form and developed it as a doctrine of the first rank.