From Slaves, To Freedmen, To Dethroners

William Edward Lecky, History of European Morals From Augustus to Charlemagne, vol. I. (New York: 3rd edt., 1897), ch. 2, The Pagan Empire, p. 233:

From the time of Caligula, for several reigns, the most influential citizens were freedmen, who occupied the principal offices in the palace, and usually obtained complete ascendancy over the emperors. Through them alone petitions were presented. By their instrumentality the Imperial favours were distributed. They sometimes dethroned the emperors. They retained their power unshaken through a succession of revolutions. In wealth, in power, in the crowd of their courtiers, in the splendour of their palaces in life, and of their tombs in death, they eclipsed all others, and men whom the early Roman patricians would have almost disdained to notice, saw the proudest struggling for their favour.