641. If someone makes eye contact with you 60% of the conversation, is bored, 80% interested in you, and 100% of the time, you are in danger.

642. Doing things that scare you will make you happier.

643. Men aren't any funnier than women, they just make more jokes without caring whether people like their sense of humor or not.

644. You rarely die in your dreams, and whenever you do, it indicates that you have started something new in your life.

645. Bilingualists may unconsciously change their personalities when they switch from one language to the other.

646. People with a generally high level of anxiety are more likely to remember images of threatening faces than people who are calmer.

647. Your body language changes with the person you talk to. Your body language seems relaxed when you talk to someone you like, while it is stiff when it's someone you don't like.

648. People who lack self-esteem need to tell others about their achievements so that their own achievements become meaningful to them. Those who have high self-esteem feel a quiet inner pride in their achievements.

649. The more you know, the more you are aware of what you don't know.

650. Optimistic beliefs about the future can protect people from physical and mental illness.