占星学将星座分成：本位、固定和变动三大特质。这三者与四种自然元素(火象、土象、风象、水象)组合之后，就衍生为十二种星座独有的特质。
The three Qualities defined in Astrology are, after the Elements, the second major classification that defines the nature of the Signs. The Qualities assign the Signs into Quadruplicities, groups of four Signs each that reflect the three common modes of Signs.
Within an astrological chart, the Quality describes a person's attitudes in life and the way they approach projects. The three Qualities are Cardinal, Fixed and Mutable.
The Cardinal Signs are Aries, Cancer, Libra and Capricorn. These four Signs are the initiators of the Zodiac. Their common characteristics include action and drive; they have initiative and strong motivation. On a team, Cardinal Signs are the people who come up with ideas and get the project moving, but they are not very good at completion and follow-through. The Cardinal Houses are the First, Fourth, Seventh and Tenth; if a chart has a number of Planets in these Houses, the chart is weighted toward Cardinal energy.
The Fixed Signs are Taurus, Leo, Scorpio and Aquarius. These four Signs are the members of the Zodiac who dedicate themselves to seeing projects through to completion. Their common characteristics include determination and persistence; they are stable and self-reliant. On a team, Fixed Signs are the people who keep a project going and see it through to the end, but they can also be stubborn and inflexible. The Fixed Houses are Second, Fifth, Eighth and Eleventh; if a chart has a number of Planets in these Houses, the chart is weighted toward Fixed energy.
The Mutable Signs are Gemini, Virgo, Sagittarius and Pisces. These four Signs are the flexible members of the Zodiac, happy to fill an assigned role. Their common characteristics include adaptability and changeability; they are flexible and versatile. On a team, Mutable Signs adapt easily to changing conditions, and they don't have a particular agenda. They can, however, be wishy-washy or inconsistent. The Mutable Houses are Third, Sixth, Ninth and Twelfth; if a chart has a number of Planets in these Houses, the chart is weighted toward Mutable energy.
Many people don't realize how important the Elements and Qualities are in true Astrology. It's the combination of Elements and Qualities that makes the Signs what they are; they combine in twelve distinct ways, one for each Sign. 中文大意：
在星相学中，不同的特质体现了一个人不同的生活态度和行事风格。其中，本位星座呈现最单纯、原始的状态；
本位星座包括白羊座、巨蟹座、摩羯座和天秤座。这四个星座是黄道带的创始者，他们共同的特性就是敢于行动，干劲十足。在一个团队里，那些颇有创意并极力推动项目实施的人肯定属于本位星座。
固定，具有顽固、最难以改变的特质；金牛座、狮子座、天蝎座和水瓶座同属于此类星座。他们共同的特质在于果断和坚持。在一个团队里，他们是最有耐心，从头至尾坚持到底的那种人，不过有时过于固执。
变动，则代表弹性和良好的调适能力；双子座、处女座、射手座和双鱼座就属于这类星座。他们的共同特质是灵活兼多才多艺。在团队中，他们是最有想法，也最善变的那种人。
很多人并没有意识到这三大特质和四种自然元素在星相学中的重要性。实际上，只有将这两种因素结合在一起，才能真实地反映星座的特点。
