Besides these books, his contributions to biology comprise several essays: “Remarks on Romanes’ _Mental Evolution in Animals_, contained in “Selections from Previous Works” (1884) incorporated into “Luck? or Cunning,” “The Deadlock in Darwinism” (_Universal Review_, April-June, 1890), republished in the posthumous volume of “Essays on Life, Art, and Science” (1904), and, finally, some of the “Extracts from the Notebooks of the late Samuel Butler,” edited by Mr. H. Festing Jones, now in course of publication in the _New Quarterly Review_. * * * * * Of all these, “LIFE AND HABIT” (1878) is the most important, the main building to which the other writings are buttresses or, at most, annexes. Its teaching has been summarised in “Unconscious Memory” in four main principles: “(1) the oneness of personality between parent and offspring; (2) memory on the part of the offspring of certain actions which it did when in the persons of its forefathers; (3) the latency of that memory until it is rekindled by a recurrence of the associated ideas; (4) the unconsciousness with which habitual actions come to be performed.” To these we must add a fifth: the purposiveness of the actions of living beings, as of the machines which they make or select. Butler tells (“Life and Habit,” p. 33) that he sometimes hoped “that this book would be regarded as a valuable adjunct to Darwinism.” He was bitterly disappointed in the event, for the book, as a whole, was received by professional biologists as a gigantic joke—a joke, moreover, not in the best possible taste. True, its central ideas, largely those of Lamarck, had been presented by Hering in 1870 (as Butler found shortly after his publication); they had been favourably received, developed by Haeckel, expounded and praised by Ray Lankester. Coming from Butler, they met with contumely, even from such men as Romanes, who, as Butler had no difficulty in proving, were unconsciously inspired by the same ideas—“_Nur mit ein bischen ander’n Wörter_.” It is easy, looking back, to see why “Life and Habit” so missed its mark. Charles Darwin’s presentation of the evolution theory had, for the first time, rendered it possible for a “sound naturalist” to accept the doctrine of common descent with divergence; and so given a real meaning to the term “natural relationship,” which had forced itself upon the older naturalists, despite their belief in special and independent creations. The immediate aim of the naturalists of the day was now to fill up the gaps in their knowledge, so as to strengthen the fabric of a unified biology. For this purpose they found their actual scientific equipment so inadequate that they were fully occupied in inventing fresh technique, and working therewith at facts—save a few critics, such as St. George Mivart, who was regarded as negligible, since he evidently held a brief for a party standing outside the scientific world.