“Associate yourself with men of good quality if you esteem your own reputation; for its better to be alone than in bad company.”

This quote implies that if you are going to have bad friends it's better to not have any at all. But if you have the right friends then you will do the right things. And when you can't find a good friend then you have to be a good friend to attract more good friends. To be able to be a good friend you have to always chose the right and show others to chose the right.