Following on his steps the poet himself professes to teach—
Quo quaeque creata
Foedere sint, in eo quam sit durare necessum,
Nec validas valeant aevi rescindere leges[43].
In another place he says—
Et quid quaeque queant per foedera naturai
Quid porro nequeant, sancitum quandoquidem extat[44].
All knowledge and speculative confidence are declared to rest on this truth—
Certum ac dispositumst ubi quicquit crescat et insit[45].
Superstition, the great enemy of truth, is said to be the result of ignorance of 'what may be and what may not be.' This is the thought which underlies and gives cogency to the whole argument. The subject of the poem is 'maiestas cognita rerum,'—the revelation of the majesty and order of the universe. The doctrine proclaimed by Lucretius was, that creation was no result of a capricious or benevolent exercise of power, but of certain processes extending through infinite time, by means of which the atoms have at length been able to combine and work together in accordance with their ultimate conditions. The conception of these ultimate conditions and of their relations to one another involves some more vital agency than that of blind chance or an iron fatalism[46]. The 'foedera naturai' are opposed to the 'foedera fati.' The idea of law in Nature, as understood by Lucretius, is not, necessarily, inconsistent with that of a creative will determining the original conditions of the elemental substances. Though the ultimate principles of Lucretius are incompatible with a belief in the popular religions of antiquity, his mode of conceiving the operation of law in the universe is not irreconcileable with the conceptions of modern Theism.