Samkhya-Yoga-Kundalini
Unlike most of the Samkhya sutras encountered up to this point, which have been fairly self-explanatory, the sutras describing the gunas are more cryptic and require some explanation. The Samkhya Pravachana Sutram and the Samkhya Karika emphasize different aspects but, even considering both sources, the picture is incomplete. Fortunately, more clarity will be found later in the study of the individual tattvas.
The difference in properties of the gunas from one another arises by means of pleasantness, unpleasantness, and dullness, etc.
By means of the properties of lightness, etc. arise both the similarities and differences of the gunas.
The gunas have the nature of pleasure, pain, and dullness, serve the purposes of illumination, activity, and restraint, and perform the functions of mutual domination, dependence, production, and association.
Sattva is considered to be light and illuminating, and rajas to be exciting and deceptive, and tamas to be heavy and obscuring indeed. Like a lamp (consisting of oil, wick, and fire), they cooperate for a purpose.
Our explanation of the gunas begins with a quote from one of the very early Samkhya teachers, Acharya Panchasikha:
What is called Sattva is of infinite variety under the forms of purity or clearness, lightness, love, agreeableness, renunciation, contentment, etc., which are summed up by the word Pleasant. Similarly, Rajas also possesses many varieties, such as grief, etc., which are summed up by the word Painful. So also does Tamas possess many varieties, such as sleep,, etc. which are summed up by the word Bewildering.
The theory of three guna is derived from properties observed in nature. All of the myriad manifestations of nature were believed to have some combination of these three properties inherent in them. For instance, there are some products or manifestations of Buddhi that are sattvic in nature, and some manifestations of Ahamkara that also are sattvic in nature. Since this quality of sattva is observed in different types of manifestations, it implies that sattva exists independent of any particular manifestation.
In contrast it is observed that not all manifestations of Buddhi or Ahamkara are sattvic in nature. Some have the nature of rajas or tamas. This implies that all three guna are present in all manifestations of Prakriti, but different guna are dominant depending on the particular instance.
In some other philosophical systems, gunas were thought of as properties or qualities of substances. In the Samkhya system, because they are the constituent parts of Prakriti, the gunas are considered to be substances themselves and their characteristics are inherent in the manifestations of nature.