On Veins and Arteries
Latin Grammar: The Irregular Verb fio
Unde Philosophus in xiv huius dicit, quod omnis operatio corporalis fit mediante corde et influentia cordis ad alias partes -- sentire est operatio corporalis et vivere -- ergo fit per medium corporale, et istud medium est arteria, quae plena est spiritu et calore naturali.
The Irregular Verb fio occurs commonly throughout Latin literature, and it can be difficult to recognize, because it is irregular. Its infinitive, ,fieri, looks like a passive infinitive but is translated in the active voice. This is because it is a deponent verb, which means that it has passive form but active voice. Fieri usually means to become or to occur, but sometimes it is translated differently (it is translated to be made in some instances). As noted earlier, the 1st person singular, present indicative active of fieri is fio.