For the artist, obscenity is an aesthetic, not a legal, problem. I wish to analyze the uses to which Catullus puts obscenity and comment on the nature of obscenity in poetry. Catullus comments on his obscene subject matter in three poems. These furnish a starting point for an anatomy of the obscenity of Catullus. Poem 50 describes an afternoon of light verse composition (versiculi) with a friend. ‘We played around a lot, each toying in verse’ (lusimus, ludebat) suggests competition, also banter and ridicule (cf. Cic. de Orat. 1.12.50). Lepor in speech is wit more than charm or pleasantness (Cic. Brut. 38. 143; also, iocum and facetiae). No doubt, then as today, a fine insult or obscenity was more immediately appreciated than a magnificent simile or compliment. No mention is made of versifying obscenity in 50, but we learn of Catullus' attitude towards writing light, and probably passionate, poetry. It is fun (lusimus), it is metrically exciting (numero modo hoc modo illoc, ‘now in this metre, now in that’), it is competitive (tuo lepore/incensus, ‘aroused by your charm’), it encourages audacity (audax), and it can leave one physically aroused.
In poem 104, Catullus claims to have been unable to insult (maledicere) his love. To ensure that no one might think him unable to write nasty, obscene poems, the fourth line insults the unknown addressee: Sed tu cum Tappone omnia monstra facis (‘But you perform every monstrosity with Bozo’).