Therefore contention too arises from anger. Now contention is often due to lack of knowledge, and by knowledge we do not impugn the truth, we know it. Therefore contention is not a daughter of vainglory. Now it is proper to pride and vainglory to seek one's own glory. And just as people are discordant when they hold to their own opinion in their hearts, so are they contentious when each defends his own opinion by words.
Consequently contention is reckoned a daughter of vainglory for the same reason as discord.
Hence it does not follow that contention arises from the same source as the raising of the voice.