Matt 7:17-20: Even so, every good tree bears good fruit, but a bad tree bears bad fruit. A good tree cannot bear bad fruit, nor can a bad tree bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire.  Therefore by their fruits you will know them.

The study of character is really the study of  how to mature into a "healthy tree" or a person who naturally inclined to do the right thing.​