"An" is used as an equivalent to "vel;"--"metu invidiae, _an_ (vel)
ratus" (II. 22,) and as if synonymous with "sive," "sive fatali
vecordia, _an_" (seu, or sive) "imminentium periculorum remedium"
(XI. 26.) In the sentence where Tiberius is described as, according
to rumour, being pained with grief at his own and the Roman people's
contemptible position for no other "reason" more than that Tacfarinas,
a robber and deserter, would treat with them like a regular enemy:--
we have the only instance in a classical composition reputed to be
written by an ancient Roman, of "alias" conveying the idea of _cause_,
instead of being an adverb of _time_:--"Nec _alias_ magis sua
populique Romani contumelia indoluisse Caesarem ferunt, quam quod
desertor et praedo hostium more agerat" (III. 73).

These errors we must believe to be the author's; considering their
gravity, we are compelled to ask ourselves the question: "Could
this writer have been an ancient Roman?" If we answer in the
affirmative, how can we explain coming repeatedly across this sort
of writing, "lacu IN ipso" (XII. 56), that is, a monosyllabic
preposition placed between a substantive and an adjective or
pronoun, a kind of composition found in the poets, but disapproved
by the prose-writers, who, if so placing a preposition, used a
dissyllable and put the adjective first. Independently of a
monosyllabic preposition thus standing frequently between a
substantive and an adjective or pronoun (judice _ab_ uno:
III. 10--urbe _ex_ ipsa: XII. 56--senatuque _in_ ipso and
urbe _in_ ipsa: XIV. 42 & 53.--portu _in_ ipso XV. 18); there
are other occasional abnormal collocations of the preposition,
such as, after two words combined by a copulative particle,
or two of them: diisque et patria _coram_ (IV. 8), Poppaea
et Tigellino _coram_ (XV. 61) and between two words connected