When we are maintaining that the existing form should be retained, we should derive material from the argument of justice, urging that it is regarded by all men as unjust to transgress the customs of our forefathers, and that all the oracles command men to make their sacrifices according to the usages of their forefathers, and that it is of the utmost importance that the religious observances should be continued which were prescribed by those who originally founded cities and set up temples to the gods.