Prudence and Virtue

http://www.answers.com/topic/virtue

Seneca, the Roman Stoic, said that perfect prudence is indistinguishable from perfect virtue. Thus, in considering all consequences, a prudent person would act in the same way as a virtuous person.

The wise person would act as if he were virtuous.  

Why and how we must try to be good

"If we are moral beings and consider ourselves to be higher than animals, we must act according to principle. Principle means doing things we know we should, but which would cause us temporary inconvenience and possibly even distress. Virtue is its own reward."