Abstract
One of the most surprising features of the final part of the fourth book of the De rerum natura is the peculiar way Lucretius introduces the topic he intends to examine at length. We approach the extensive treatment of love from merely physiological phenomena. The terms libido and amor are mentioned for the first time at 1045 and 1046 respectively; I would like to focus on the interpretation of those lines and on the meaning of the clausula dira libido in the context of the final section of Book Four. Lucretius is talking of semen: quod simul atque suis eiectum sedibus exit, per membra atque artus decedit corpore toto, in loca conveniens nervorum certa cietque continuo partis genitalis corporis ipsas. irritata tument loca semine fitque voluntas 1045 eicere id quo se contendit dira libido, idque petit corpus mens unde est saucia amore