These modes are termed in the Indian books qualities, gunas, and are given the names sattva, rajas, tamas. Sattwa is the force of equilibrium and translates in quality as good and harmony and
happiness and light; rajas is the force of kinesis and translates in quality as struggle and effort, passion and action;
tamas is the force of inconscience and inertia and translates in quality as obscurity and incapacity and inaction. Ordinarily used for psychological self-analysis, these distinctions are valid also in physical Nature. Each thing and every existence in the lower Prakriti contains them and its process and dynamic form are the result of the interaction of these qualitative powers.

The Godhead, the spirit manifested in Nature appears in a sea of infinite quality, Ananta-guna. But the executive or mechanical Prakriti is of the threefold guna, sattwa, rajas, tamas, and the Ananta-guna, the spiritual play of infinite quality, modifies itself in this mechanical nature into the type of these three gunas.

This earth alone is not our teacher and nurse;
The powers of all the worlds have entrance here.
In their own fields they follow the wheel of law
And cherish the safety of a settled type;
On earth out of their changeless orbit thrown
Their law is kept, lost their fixed form of things.