1 This interpretation is laid out in an excellent paper by A. Traina, Dira libido. (Sul linguaggio lucreziano dell'eros), in Sludi di letteratura latina in onore di A. Traglia (Rome, 1979), i. 259–76, now in Traina A., Poeti latini (e neolatini) II (Bologna, 1981), pp. 11 ff. Traina rightly points out the reticence of the editors, among whom only Leonard and Smith (Madison, 1942) have anything to remark on dira (but, as Traina says, their opinion, ‘dira …a Puritanical and conventional epithet for unchastened desire’, misses the point). The situation has not significantly changed: J. Godwin (Warminster, 1980) remains silent, and R. Brown (Amsterdam, 1988) basically agrees with Traina.
2 One of the meanings of dirus (generically: ‘terrible’) is ‘unnatural’, to be taken more precisely as ‘absurd’, ‘senseless’. For Lucretius, love is not only excessive, inasmuch as it takes away Epicurus' disciple from the search for ⋯ταραξ⋯α and wisdom, but altogether unnatural: it is absurd to hope that the source of passion and the means to quench it can come from the same person, quod fieri contra totum natura repugnat (1088). Cf. Hor. Carm. 2.2.13ff. (crescil indulgens sibi dirus hydrops / nee sitim pellit, nisi causa morbi / fugerit venis), where dirus not only describes the repelling aspect of the dropsical, but indicates as well the mistake he is led into, the indulgentia sibi, the fact that he goes on drinking instead of trying to eliminate the causa morbi (cf. Nisbet and Hubbard ad loc).
3 Hier. Chron. s.a. 1923 Helm; DrLogre , L'anxiété de Lucrèce (Paris, 1946).
4 Lucretius' polemical target should therefore be seen in the traditional portrait of love as only metaphorically terribilis, δiν⋯ς. On the contrary, Love is actually dirus (whether or not the two adjectives are etymologically connected). It is a flame that, as Nature herself teaches all too well, cannot be put out by water coming from the same source as the fire: ⋯ ταώσας, for Lucretius, oὐκ ἰ⋯σταi (cf. Otto, Sprichwörter, s.v. amor).
5 Impensus does not have any negative implication, and can be referred to positive qualities as well. This is the first time that the adjective is used in poetry: cf. ThLL vii.l, p. 548, 73.