At the higher levels of Ballroom Dancing, the dance partnership is divided into three distinct sections: the Yin-Yang Core in the center, the "Above" the Core section and the "Below" the Core section. Each individual partners' core is one half of the Yin-Yang Core (the Yin is the feminine part and the Yang is the masculine part). The attraction of the Yin and Yang creates the complete Yin-Yang Core of the partnership. I am deliberately using the term "attraction" instead of "connection". I think of a "connection" as being a solid, rigid, physical, type of association between two entities but I envision "attraction" as a soft, pliable, complementary type of association of the two entities. However, there is one type of action going on "Above" the Yin-Yang Core and a different type of action going on "Below" the Yin-Yang Core.
"Above" the Yin-Yang Core is the personality of the partnership and the melody of the music. I'm sure you have heard of the term "Big Top Line" in Ballroom Dancing. It sits on top of the Yin-Yang Core and portrays the character and feeling of the dance. The expression of the character and feeling of the dance comes through the action of the upper body above the Yin-Yang Core. The head, hands, arms, shoulders, chest, back and waist, all participate in creating the expressions of the dance.
The Yin-Yang Core is a result of the Yin-Yang "attraction" and is the central component of the partnership that holds the three sections together. The Core is the reference point of the complete partnership. The Core is the where the power as applied for the movement of the partnership. The Yin-Yang Core is where the Latin/Cuban Motion is performed. The Core is also the stabilizing piece that allows the "Above" and the "Below" sections to act separately and differently.
"Below" the Yin-Yang Core is the support, locomotion, and power of the partnership as well as the rhythm of the music. The feet (balls, heels and ankles) and legs (knees, hips) all participate in developing the power for locomotion in the horizontal, vertical and rotational directions of the dances' movements. They also create the hip action known as Latin/Cuban Motion. The legs can also move in a two, three and four legged manner, independent of the actions going on in the "Above" section of the partnership. The "Below" section moves in such a manner as to interpret the rhythm of the music being played (rise and fall, strong staccato movements, smooth and even movements, rotating movements, etc.).
It is as if "Above" the Yin-Yang Core is performing the melody of the music and "Below" the Yin-Yang Core is performing the rhythm of the music and supplying the power for the movements. The Yin-Yang Core holds it all together. It takes time to be able to coordinate the three levels to create the feeling of oneness. The dancers will always be in the most optimum partnership (two-headed four-legged) position by simply maintaining the Yin-Yang Core.