There are two sections, the top which shows willpower and the bottom which shows just how much you will push to get what you want. Large thumbs show a strong personality.
Small thumbs show the person is gentler. Long, broad thumbs belong to people who push hard and succeed.
Long, narrow thumbs belong to people who want to succeed but don't have the driving force. Small, broad thumbs belong to people who lack determination.
Thumbs that have an exceptionally wide top belong to aggressive people. If the other applies and the top is very narrow it indicates a sign of weakness.
A thick top joint shows a person who is blunt. The tapered tip shows a subtle way of doing things.
A thumb that holds itself close to the side of the hand shows a stingy person. A thumb that sticks out indicates a carefree personality.