We often group the zodiac signs into four elements: fire, air, earth and water, but this is actually just one of many ways astrologers group them.
Another way astrologers have grouped the 12 signs is to separate them into three modalities. These modalities separate the signs based on the way their "modus operandi," or the way they operate.
Each of the modalities has a distinct quality. They're known as Cardinal, Fixed and Mutable, and they each have a unique way of engaging with the world.
Cardinal signs are leaders. They have an initiatory spirit, and the charisma to inspire large groups to take action. Their sign characteristics determine their particular style of leadership.
They are self-starter types, and as children they may have been extremely active and dynamic. Their lives are marked by challenges having to do with their circumstances changing, and the proper use of their power.
These signs have a lot of start-up power, but follow-through can be difficult for them. Teaming up with a fixed sign can be beneficial for them in situations when they run into a problem and want to give up.
Someone with a birth chart that has bunch of planets in cardinal signs may be a bit of a procrastinator.
Fixed signs are unsurprisingly stubborn, fixated, and unyielding, but these aren't negative qualities. These qualities endow fixed signs to be more loyal and persevering than the others. They stick to their ideas and see them through through any and all challenges that come up.
These signs will have their lives marked by challenges having to do with things getting in the way of their desires, and their willingness to let go of an idea or ideal when it has stopped working for them.
The Fixed signs dig in and are able to hold steady in their goals to achieve something solid. It's hard for them to change, which gives them a reputation for being stubborn. But they are respected for their self-containment and sense of purpose.
Mutable Signs: Sagittarius, Pisces, Gemini, And Virgo
Mutable signs are flexible, impressionable, and absorbent people. They may feel restless a lot, because they desire change and function well under changing circumstances with an inherent ability to ride the tide.
These signs' lives will be marked by challenges having to do with overcoming their fears. They can be a very sensitive, skittish bunch, but have immense reserves of strength to overcome these challenges within them.
These signs may pick up or mimic the qualities of whomever they spend the most time with because of how impressionable they are, but this also endows them with an ability to pick up new knowledge or skills fairly easily and to make them their own over time.