What does Creon beilieves shows "the soul, the mind, the intent of a man"?

"No man can be fully known, in soul and spirit and mind, until he hath been seen versed in rule and law-giving. For if any, being supreme guide of the state, cleaves not to the best counsels, but, through some fear, keeps his lips locked, I hold, and have ever held, him most base; and if any makes a friend of more account than his fatherland, that man hath no place in my regard."