Lucretius’ poem, for which Epicurean philosophy provided the inspiration, attempts to explain the nature of the universe and its processes with the object of freeing mankind from religious fears. The third book not only seeks to demonstrate that, since the soul is mortal, there can be no after-life, but also aims to reconcile the reader to the prospect of the end of his consciousness. This edition incorporates a new text and prose translation and is designed to set the book in the context of the whole poem and of the Epicurean philosophical system, to explain and elucidate its argument, and at the same time to analyse some of the literary and artistic features which contribute to Lucretius’ poetic achievement and stature.