In every astrological modalities, cardinal, fixed and mutable, there are four zodiac signs that belongs to them. These four-sign groups are known as quadruplicities. Signs that are grouped together in each mode, 
share the same essential and key qualities. However, they also have many individual differences.
Cardinal
Signs that belong to this are Aries, Cancer, Libra and Capricorn. Each of the them falls on either a solstice or
an equinox and the change of seasons. The solstice signs are Cancer and Capricorn. The equinox signs are
Aries and Libra. Aries represents spring; Cancer brings on summer; Libra introduces fall; and Capricorn
reflects winter. This is why they are associated with new beginnings. Cardinal signs are initiators,
enterprising, creative in character, assertive and at times seemingly aggressive. However, they do get things
done. They are an unstoppable force and are direct and decisive.
Fixed
The fixed signs are Taurus, Leo, Scorpio and Aquarius. They appear in the middle of one of the four seasons. Taurus is found in the middle of spring; Leo is found in the middle of summer; Scorpio is found in the middle of fall; and Aquarius is found in the middle of winter. They represent stability, reliability and determination. They can also be resistant to change and stubborn at times. But they are goal-oriented and willing to do whatever it takes to accomplish what they have set out to do.
Mutable
Included in the mutable signs are Gemini, Virgo, Sagittarius and Pisces. Each of these signs appears at the
change of the four seasons, which reflects the changeability associated with them. Gemini represents the end
of spring and the beginning
of summer. Virgo transitions the end of summer to the beginning of fall. Sagittarius transitions the end of fall and brings us into winter. Pisces represents the end of winter and the beginning of spring. These signs are adaptable and flexible which means they are able to go with the flow, no matter what the circumstance. In fact, they are able to see all sides of a situation and are also excellent in handling a crisis. By nature, mutable signs are communicative and sometimes their energies may be misconstrued as being rebellious.
Grouping zodiac signs based on quadruplicities adds a new dimension to understanding their shared and unique qualities.
The classification of zodiac signs based on their modalities is quite intriguing. It provides a structured perspective on their characteristics.
The stability and resistance to change in fixed signs align well with their placement in the middle of seasons.
It is fascinating how cardinal signs’ placement at equinoxes and solstices translates into their initiating characteristics.
The mutable signs’ communicative nature and adaptability are well-portrayed through their ability to transition between seasons smoothly.
The adaptive nature of mutable signs makes sense given their transitional roles between seasons.
Indeed, the flexibility of mutable signs appears to parallel the shifting of seasons.
Their ability to handle crises might stem from their inherent adaptability.
The correlation between cardinal signs and the start of seasons gives a logical explanation for their traits of initiation and assertiveness.
Fixed signs being goal-oriented and determined fits well with their seasonal positioning.