Of the five essays in this volume, two only, those on "The Past" and "Luck," were written in 1901. The others, "The Mystery of Justice," "The Evolution of Mystery," and "The Kingdom of Matter," are anterior to "The Life of the Bee," and appeared in the Fortnightly Review in 1899 and 1900. The essay on "The Past" appeared in the March number of the Fortnightly Review and of the New York Independent; and parts of "The Mystery of Justice" in this last journal and Harper's Magazine. The author's thanks are due to Messrs. Chapman & Hall, Messrs. Harper & Brothers, and the proprietors of The Independent for their permission to republish.