There are three friendships which are advantageous, and three which are injurious. Friendship with the upright; friendship with the sincere; and friendship with the man of much observation: these are advantageous. Friendship with the man of specious airs; friendship with the insinuatingly soft; and friendship with the glib-tongued: these are injurious.
ConfuciusLearn as though you would never be able to master it; hold it as though you would be in fear of losing it.
ConfuciusWe can know a person by observing his behaviour, understanding the reasons for his actions and ascertaining his intentions. If we do this, how can we not know him?
Confucius