Indebtedness to editors of Seneca and to others, which has been very great, is acknowledged as fully as possible in the Introduction and elsewhere where help has been availed of. The interest taken in the book by various friends is also gratefully acknowledged. Professor Sir Joseph Larmor and Professor J. Arthur Thomson have made several useful suggestions. Professor Herbert J. C. Grierson has very kindly read the proofs and given valuable assistance in other respects. But my chief acknowledgments are due to Sir Archibald Geikie. To him the translation owed its inception: his constant aid and encouragement have enabled me to complete a task from which I should probably have otherwise shrunk. I am indebted to him also for the Commentary appended to the translation, in which the questions treated by Seneca are considered from the point of view of modern Science. It has been to him a labour of love: may our readers enjoy something of the same satisfaction! J. C. Old Aberdeen, _September 27, 1909_. CONTENTS PREFACE v INTRODUCTION xxi BOOK I [METEORS, HALO, RAINBOW, MOCK SUN, ETC.] PREFACE PAGE Contrast between human (moral) philosophy and divine (natural, physical). The sublime character of the latter which lifts us above the contemplation of the littlenesses of the earth and earthly life to the knowledge of God and His nature. Compared with astronomical conceptions and dimensions the world of man is but as a threshing-floor, the haunt of ants. The mind of man attains its true height in contemplation and investigation of these sublime facts. Some of the problems thus raised 3 CHAP. I. Meteoric fires--_she-goat_, _kid_, etc. Occasions of their appearance; connection of portent with event. Explanation of the phenomena. They may be due to pressure of the atmosphere. Aristotle attributes them to the effect of terrestrial evaporation: difference of density causes various outbursts of this kind. They are analogous to lightning, but less violent 8