M. Caelius Rufus was probably born in 88 or 87. This would accord with the facts of his public career (aedile 50, praetor 48: MRR ii 248, 273) in spite of Pliny's claim that he was born on the same day (28 May 82) as the poet and orator C. Licinius Calvus (Nat. 7.165), an apparent mistake. From an early age he was educated in the house of the later “triumvir” M. Licinius Crassus, no doubt along with Crassus’ younger son Publius (§9). Upon reaching maturity, perhaps ca. 72, he was placed in the care of C. for the traditional apprenticeship of a young man destined for work in the courts and public life generally (tirocinium fori: ibid. with n.). C. suggests that he continued in this tutelage during the following years, though one might query whether he has not, for the sake of his case, exaggerated the closeness of the relationship. As late as 64 he still stood by C. in his candidature for consul (§10); only the following year did he deviate, perhaps under Crassus’ influence, by supporting Catiline's consular candidature (§11 with n.). C. is keen to deny that his client was Catiline's lover or that he supported his revolution (§§12 and 15). But Caelius was prosecuted in 50 by Servius Pola under the lex Scantinia (banning homosexual activity: TLRR 347; Rotondi : 293) and in 48 promulgated a bill calling for cancellation of debts (nouae tabulae: Caes. Civ. 3.21.2; Vel. 2.68.2; Dio 42.22.4), a key point in Catiline's program (Sal. Cat. 21.2). Though C. denies that there was “so great a wound” (tantum…uulnus) in his client as to draw him into the conspiracy (§15), Caelius’ father was stingy (§36 patre parco ac tenaci) and his expenditures large (§17; cf. the remark, albeit ironic, at §27 qui nullum conuiuium renuerit, qui in hortis fuerit, qui unguenta sumpserit, qui Baias uiderit); his youth and his debts (if the charge at §17 is true would match the profile of some of Catiline's followers (Catil. 2.8 and 22–3; Sal. Cat. 14).