Macrinus

It had hitherto been considered as a fundamental maxim of the constitution, that the emperor must be always chosen in the senate, and the sovereign power, no longer exercised by the whole body, was always delegated to one of its members. But Macrinus was not a senator. The sudden elevation of the Praetorian praefects betrayed the meanness of their origin; and the equestrian order was still in possession of that great office, which commanded with arbitrary sway the lives and fortunes of the senate. A murmur of indignation was heard, that a man whose obscure extracdtion had never been illustrated by any signal service, should dare to invest himself with the purple, instead of bestowing it on some distinguished senator, equal in birth and dignity to the splendor of the Imperial station.

As soon as the character of Macrinus was surveyed by the sharp eye of discontent, some vices, and many defects, were easily discovered. The choice of his ministers was in many instances justly censured, and the dissatisfied people, with their usual candor, accused at once his indolent tameness and his excessive severity.

His rash ambition had climbed a height where it was difficult to stand with firmness, and impossible to fall without instant destruction.

–Edward Gibbon, The Decline and Fall of the Roman Empire