The mound that forms the ball at the base of the thumb is ruled by Venus.
Astrologically Venus is the ruler of the zodiac signs of Taurus and Libra and it is at home in the 2nd and 7th houses of the wheel. As Libra Venus is Air and as Taurus it is Earth.
Mythology
Venus was originally a Goddess of Spring, fruitfulness, herbs and flowers. She later became identified with the Greek Aphrodite and took on her associations of love and sexuality. Aphrodite was married to the god of smiths, Hephaistos, but had many affiars with both gods and men. Aphrodite was the patroness of prostitutes.
Astrological Meaning
Venus in the Natal chart represents love, feeling, harmony, devotion, esthetics, luxury, value, play, the ability to give and take, partnership and relationship. It can also denote areas of temptation or the capacity to devote oneself to someone or something. Venus is the feminine principle.
Positively, Venus can be sensuous, playful, warm-hearted, affectionate, empathic and well-mannered. In its negative state venus can be vain, superficial, tastleless, perverse, jealous, cruel, greedy, lazy, snobbish and infantile.
Venus in your Hand
The mound of Venus is an indicator of our ability to love as well as our capacity for playfulness. It indicates the strength and energy of our physical appetites, our zest for life. A normal mound of Venus suggests warmth and a balanced attitude toward the physical manifestations of love.
An excessively large mount of Venus is an indicator of someone who lets their desires run the show. Appetites and emotions may be exaggerated and this person can be crude and brutish. An underdeveloped mound of Venus implies insecurity or lack of zest for life. It is often accompanied by a life line that runs closely around the thumb.