Two volumes (1924; 1926). Second edition, second impression (reprints of 1912; 1917). Large 8vos, pp. xxi, (3), 716; xix, (1), 865, (3) press opinions. Olive green cloth with gilt stamped lettering and ruling to spine, blind stamped ruling to boards. Untrimmed edges, some pages uncut. Shelf wear to boards. Bruising and wear to spine ends and corners, bald patches to heel of spine of both vols. White paint stain to lower board of vol. I, blue paint streak to upper board of vol. II. Endpapers tanned, pencil scoring and marginalia throughout both vols. Else, clean. Arguably the definitive edition, for, as Westermarck notes in his prefaces to the second editions, inaccurate expressions have been corrected and further notes added. The Finnish sociologist and philosopher (1862–1939) played a central role in introducing sociology to British universities, and, alongside sexologists like Havelock Ellis, in unsettling normative ideas about sexuality. Westermarck's voluminous study of moral ideas took 20 years to research, including field work in Morocco. This study comprises 'a vast compendium of moral practices and beliefs,' which Westermarck drew upon to underpin his argument that moral judgements do not have objective validity (Stroup, DNB). 'In Dr. Westermarck's hands a subject which might be impossibly abstruse becomes almost as attractive as a romance.' (Yorkshire Post).