Full Idea
In the case of virtue excess should not be feared, since in virtue resides moderation.
Gist of Idea
Virtue is always moderate, so excess need not be feared
Source
Seneca the Younger (On the Happy Life [c.60], §13)
Book Reference
Seneca: 'Dialogues and Essays', ed/tr. Davie,John [Penguin 2007], p.96
A Reaction
This seems to imply that all of the virtues are unified in the one achievement of the virtuous state. It leaves the notion of 'virtue' a bit thin in content, though.