Charles E. Bennett, New Latin Grammar
“ In letters the writer often uses tenses which are not appropriate at the time of writing, but which will be so at the time when his letter is received; he thus employs the Imperfect and the Perfect for the Present, and the Pluperfect for the Present Perfect; as,—nihil habēbam quod scrīberem, neque enim novī quidquam audieram et ad tuās omnēs epistulās jam rescrīpseram, I have nothing to write, for I have heard no news and have already answered all your letters. ”
