Fortified by this knowledge against heathen views, let us rather turn to the unworthy reasonings of our own people; for the faith of some, either too simple or too scrupulous, demands direct authority from Scripture for giving up the shows, and holds out that the matter is a doubtful one, because such abstinence is not clearly and in words imposed upon God's servants. Well, we never find it expressed with the same precision, “You shall not enter circus or theatre, you shall not look on combat or show;” as it is plainly laid down, “You shall not kill; you shall not worship an idol; you shall not commit adultery or fraud.” But we find that that first word of David bears on this very sort of thing: “Blessed,” he says, “is the man who has not gone into the assembly of the impious, nor stood in the way of sinners, nor sat in the seat of scorners.” Though he seems to have predicted beforehand of that just man, that he took no part in the meetings and deliberations of the Jews, taking counsel about the slaying of our Lord, yet divine Scripture has ever far-reaching applications: after the immediate sense has been exhausted, in all directions it fortifies the practice of the religious life, so that here also you have an utterance which is not far from a plain interdicting of the shows. If he called those few Jews an assembly of the wicked, how much more will he so designate so vast a gathering of heathens! Are the heathens less impious, less sinners, less enemies of Christ, than the Jews were then? And see, too, how other things agree. For at the shows they also stand in the way. For they call the spaces between the seats going round the amphitheatre, and the passages which separate the people running down, ways. The place in the curve where the matrons sit is called a chair. Therefore, on the contrary, it holds, unblessed is he who has entered any council of wicked men, and has stood in any way of sinners, and has sat in any chair of scorners. We may understand a thing as spoken generally, even when it requires a certain special interpretation to be given to it. For some things spoken with a special reference contain in them general truth. When God admonishes the Israelites of their duty, or sharply reproves them, He has surely a reference to all men; when He threatens destruction to Egypt and Ethiopia, He surely pre-condemns every sinning nation, whatever. If, reasoning from species to genus, every nation that sins against them is an Egypt and Ethiopia; so also, reasoning from genus to species, with reference to the origin of shows, every show is an assembly of the wicked.
Source: De Spectaculis (The Shows) (New Advent)