September 13 was also the day on which, according to Livy[1020] and Verrius Flaccus[1021], a nail (_clavus_) was driven _annually_ by the ‘Praetor maximus’ into the wall of the cella of Minerva in the Capitoline temple, in obedience to an old lex which was fixed up on the wall of the temple adjoining this same cella. But Mommsen’s trenchant criticism[1022] of the _locus classicus_ for this subject in Livy has made it almost certain that the Roman scholars were here in error: that the ceremony was not an annual one, but took place once in a century, in commemoration of a vow made in 463 B.C., to commemorate the great pestilence of that year, which carried off both the consuls and several other magistrates[1023]: that it had no special connexion with the cult of Jupiter, and was not intended, as is generally supposed, to mark the years as they passed. The nail is really the symbol of Fortuna or Necessitas; the rite was Etruscan, and was also celebrated at Volsinii in the temple of the Etruscan deity of Fate; when brought to Rome it was very naturally located in the great temple of the Etruscan Trias, the religious centre of the Roman state. Originally a dictator was chosen (i. e. Praetor maximus) _clavi figendi causa_; and when the dictatorship was dropped after the Second Punic War, the ceremony was allowed to fall into oblivion. Later on the Roman antiquarians unearthed and misinterpreted it, believing it to have been a yearly rite of which the object was to mark the succession of years. This brief account of Mommsen’s view may suffice for the purpose of this work: but the subject is one that might with advantage be reinvestigated. Footnote 930: This represents the length which the ludi had attained in Cicero’s time (_Verr._ i. 10. 31). September 4 was probably added after Caesar’s death (Mommsen in _C. I. L._ 328). Footnote 931: _C. I. L._ 281. Footnote 932: _R. R._ I. 33. Footnote 933: See Mommsen’s masterly essay in his _Römische Forschungen_, vol. ii. p. 42 foll. Aust, in _Myth. Lex._ s. v. Iuppiter, 732. Footnote 934: Mommsen, _Röm. Chronol._ 86 foll. Footnote 935: The ‘equorum probatio,’ preliminary to the races in the circus, took place on the day after the Ides: see above, p. 27. Footnote 936: Mommsen (_C. I. L._ 328, and _Röm. Forsch._ ii. 43 foll.) points out that the real centre-point and original day of the ludi proper was the day of the great procession (pompa) from the Capitol to the Circus maximus; and that this was probably the 15th, two days after the epulum, because the 14th, being _postriduanus_, was unlucky, and that day was also occupied by the ‘equorum probatio.’ (See Fasti Sab., Maff., Vall., Amit. and Antiat.) Footnote 937: See below, p. 234. For the _dies natalis_, see Aust, in _Lex._ s.v. Iuppiter, p. 707; Plutarch, _Poplic._ 14. Footnote 938: Mommsen, _Röm. Forsch._ l. c. Footnote 939: