This paper aims to investigate the equivalent of Epicurus’ πρόληψις, the second criterion of the Epicurean Canonic (DL X 31 = fr. 35 Usener), in Lucretius’ De rerum natura (DRN). Taking stock of the several occurrences of the Latin terms notitia and notities in the six books of the poem, I show that Lucretius’ view about preconception remains faithful to Epicurus’ πρόληψις, and that the poet does not endorse a less empiricist position than his Master because of some influence of (...) the Stoic ἔννοια. To this end, I will also briefly address an important case in which πρόληψις, albeit not clearly mentioned, plays an essential role, namely the prolepsis of the deity (DRN V 1169–1182). Finally, I explain how Lucretius can be of some help in grasping the controversial relationship between the criterion of πρόληψις and that of ἐπιβολὴ τῆς διανοίας (animi inectus/iactus), showing in which way the poet seems to consider the latter as a criterion of truth in its own right. (shrink)