A Dictionary of Greek and Roman biography and mythology

4. Cn.Seius, had the finest horse of his age, which was fated to bring destruction to whoever possessed it. Seius was condemned and put to death by M. Antonius, afterwards the triumvir, apparently during the civil war between Caesar and the Pompeians. This horse then passed into the hands of Dolabella, and afterwards into those of Cassius, both of whom perished by a violent death. Hence arose the proverb concerning an unfortunate man : ille homo habet equum Sejanum. (Gel. 3.9.)