Calm or Undifferentiated Mind.
"The spiritualized Atom, in which Ahamkara (the idea of separate existence of Self) appears, has five manifestations (aura electricities).
"They (the five aura electricities) constitute the causal body of Purusha.
"The five electricities, Pancha Tattwa, from their three attributes, Gunas - Sattwa (positive), Rajas (neutralizing), and Tamas (negative) - produce Jnanandriyas (organs of sense), Karmendriyas (organs of action), and Tanmatras (objects of sense).
"These fifteen attributes plus Mind and Intelligence constitute the seventeen "fine limbs" of the subtle body, the Lingasarira." (Swami Sri Yukteswar, The Holy Science, Sutra 7-10)
7.8 - Matter and Spirit are Opposite Poles
8.26 - Law of Force