It remains for us to examine the “spectacle” most noted of all, and in highest favour. It is called a dutiful service (munus), from its being an office, for it bears the name of “officium” as well as “munus.” The ancients thought that in this solemnity they rendered offices to the dead; at a later period, with a cruelty more refined, they somewhat modified its character. For formerly, in the belief that the souls of the departed were appeased by human blood, they were in the habit of buying captives or slaves of wicked disposition, and immolating them in their funeral obsequies.
Afterwards they thought good to throw the veil of pleasure over their iniquity. Those, therefore, whom they had provided for the combat, and then trained in arms as best they could, only that they might learn to die, they, on the funeral day, killed at the places of sepulture. They alleviated death by murders. Such is the origin of the “Munus.” But by degrees their refinement came up to their cruelty; for these human wild beasts could not find pleasure exquisite enough, save in the spectacle of men torn to pieces by wild beasts.
Offerings to propitiate the dead then were regarded as belonging to the class of funeral sacrifices; and these are idolatry: for idolatry, in fact, is a sort of homage to the departed; the one as well as the other is a service to dead men. Moreover, demons have abode in the images of the dead. To refer also to the matter of names, though this sort of exhibition has passed from honours of the dead to honours of the living, I mean, to quæstorships and magistracies— to priestly offices of different kinds; yet, since idolatry still cleaves to the dignity's name, whatever is done in its name partakes of its impurity.
The same remark will apply to the procession of the “Munus,” as we look at that in the pomp which is connected with these honours themselves; for the purple robes, the fasces, the fillets, the crowns, the proclamations too, and edicts, the sacred feasts of the day before, are not without the pomp of the devil, without invitation of demons. What need, then, of dwelling on the place of horrors, which is too much even for the tongue of the perjurer? For the amphitheatre is consecrated to names more numerous and more dire than is the Capitol itself, temple of all demons as it is. There are as many unclean spirits there as it holds men. To conclude with a single remark about the arts which have a place in it, we know that its two sorts of amusement have for their patrons Mars and Diana.
Source: De Spectaculis (The Shows) (New Advent)