This thesis considers how persistent, coherent patterns of imagery explain the fundamental laws and processes of Lucretius' science and philosophy. It will show how these patterns, taken from human experience, serve to guide the reader through the difficult, and at times unpalatable, doctrines of Epicureanism. Frequently they take the form of metaphors explaining scientific realities, but often they are employed literally, which in turn strengthens their metaphorical application. Inspired by Lucretius' weaving metaphors for argumentation, and the complex web these images form, I have labelled them 'conceptual threads'. This term expresses how they develop and intertwine as the epic progresses. The present work builds on existing scholarship which has established the importance of imagery to Lucretius' De Rerum Natura (DRN) and its interpretation, but the coherence of the patterns of imagery across the whole poem has not hitherto been appreciated. In 1949 Stella Pope wrote as follows: 'It is possible that some of the problems in Lucretius will be resolved by a consideration of his imagery in its richness and variety, the reality which it gives to theoretic processes, and the clarity with which abstractions are realized. In this may lie the explanation of the passionate invocation to Venus at the outset of the poem attacking orthodox religion, and the emotional fervour which pervades Lucretius' exposition of his scientific philosophy. Certainly when one has tried to understand his imagery the rigid cleavage which some have seen between scientific and poetic parts of the De Rerum Natura no longer seems to exist.'1