Also known as the quadruplicities, there are three modalities: Cardinal, fixed, and mutable. The modalities are often associated or even considered to be the same as the traditional alchemical or magickal elements: fire, earth, air, and water. However, it's more accurate to describe them as the way an element functions, rather than the element itself. 

• The Cardinal signs are Aries, Cancer, Libra, and Capricorn. Cardinal signs are considered to be pioneers, but once they explore or start something they can get bored or tired of it and give it off to someone else. Someone born under a Fixed sign is the likely recipient for this. 
• The Fixed signs are Taurus, Leo, Scorpio, and Aquarius. "Fixed" is a good description, as people born under these signs are often quite "fixed" in their ways. This is good for achieving stability, but they also can exhibit stubbornness. 
• The Mutable signs are Gemini, Virgo, Sagittarius, and Pisces. People born under one of these signs can be flexible and adaptable, but they can also be fickle and changeable.