The reviewer's copy of the first edition of this book, published in 1971, has scribbled inside the front cover ‘1st Arts, QUB’. That means that the third book of Lucretius was one of his set texts when he was a first-year undergraduate in Belfast during the academic year 1978–1979. During the academic year 2015–2016 he will be using the new second edition of this excellent commentary with his first-year students in Geneva. Back then, K. was Reader in Latin Literature and Textual Criticism at Cambridge. Now he is Kennedy Professor Emeritus, after a highly distinguished career. The commentary has been ‘extensively revised and enlarged’ (p. xi), some sections of the introduction have been rewritten and a supplementary introduction also added. The bibliography has been brought up to date. It is noteworthy how much fine scholarship has been published since 1971: important work by D. Fowler, M. Gale, A. Schiesaro, D. Sedley and many others has enriched our understanding of this extraordinary poem, just as P. Hardie had revolutionised our understanding of its impact on Virgil. And, of course, discoveries such as the Strasbourg Empedocles, the Herculaneum papyri and many new pieces of the great inscription of Diogenes of Oenoanda have also come to light. K. regrets (p. xi) that it has not been possible to include mention of all the work of M.F. Smith on the latter, and that is indeed a great pity. For the history of the text, he has been able to take fully into account recent work by D. Butterfield on the early transmission. The first edition of this book quickly established itself as a classic of its kind and set high standards for the series in which it appeared, the Cambridge Greek and Latin Classics, of which K. was one of the founding editors. In this journal in 1974 M.F. Smith wrote thus: ‘The commentary is scholarly, thorough, perceptive, and economical. The treatment of stylistic and linguistic matters is particularly good’. As the series of Cambridge ‘green and yellows’ continues to flourish, with K. still acting as one of the General Editors, this excellent new edition will be warmly welcomed by all those involved in the serious study of Lucretius.