Śiva, the Auspicious, simultaneously beautiful, loving, merciful, and awful, is said by His Yogis and Bhaktas to be none other than the Uncreate Reality beyond all qualities; others say of Him that He is the essence of tamoguna, the quality or tendency to crystallization, involution, and inertia. There is a clear contradiction, here, for it is not right to say of Godhead that He is characterized by anything, let alone by materiality, density, and sloth! We can say of Śiva, however, that He is certainly the resolution of all paradoxes. The contradictory attributions made of Him in Scripture and philosophy always point beyond themselves to a more essential element.
The twenty-five tattvas (ontological principles) of Sāṃkhya — ranging from the gross elements of earth, water, fire, air, and space, through the subtle bodies, to the two essentials of prakṛti (nature) and puruṣa (literally “man”, but in this context “spirit” is more direct) — describe, among other things, the codependent arising (in the Buddha’s sense) and expression of the three gunas. Those “thread-like qualities” make up the warp and woof of the entire created universe; they exist in chaotic potential within primordial prakṛti until manifestation is necessitated by her interaction with the orderly puruṣa. It is within this matrix that the so-called trimūrti of Brahmā, Viṣnu, and Śiva (in His form of Rudra, the Howler) is established as the personalities of the gunas, such that Brahmā = rajas (expansiveness), Viṣnu = sattva (peacefulness), and Rudra-Śiva = tamas (inertia and dissolution).
Reality is, however, essentially and ultimately non-dual. As such, Śaiva cosmology sees an additional eleven tattvas yet more subtle than the twenty-five. These trans-creational or supramanifest principles include the modes by which the Divine self-limits or contracts in order to “make way” for creation, and even include — in conceptual form, and only in order to provide a kind of map or diagram of sublimation and ascension — the unmanifest Godhead Itself. In short, Śaiva Sāṃkhya is a view of Sāṃkhya in its methodological, rather than speculative, aspect. It is seen equally in Kashmir Śaivism and in the Tamil Vedānta-Siddhānta of Sage Tirumūlar, in varying degrees of explicit exposition, but ultimately forms the base of all Śaivism.
At any rate, it ought to be clear that, beyond the level of prakṛti, the gunas do not obtain. Simply put, they only exist as the raw materials of the chaos from which manifestion issues; any more subtle application of the idea of the gunas is purely abstract and speculative.
An additional point bears on the present discussion: that Śiva is not (as is probably clear, by now) limited to a mere function. By His interactions with them, Śiva makes quite clear that Brahmā, Viṣnu, and Rudra are His functions, arising as graces from His more transcendent graces of Maheśvara (veiling grace) and Sadāśiva (revealing grace). So, the gunas manifest particular processes which, if we may so speak, issue from Śiva as both efficient and material cause, but in no way define Him.
There is a sense, however, in which we may discuss the gunas above prakṛti, and this sense, as previously suggested, is in the abstract — a means for the human mind to relate to Essence by way of contingency. This usage is illustrated explicitly in the well-known image of Kālī standing or dancing upon the corpse of Lord Śiva. Here, Kālī is the Mahāśakti or, more precisely, Paraśakti from Whom and by Whom even the six limiting principles, puruṣa, and prakṛti arise prior to the act of creation. As such, Hers is the entire process of creation, preservation, and destruction. Her passionate dance and violent power allow us to call Her — provisionally! — rajasic. The “corpse” of Śiva under Her feet presents to us Śiva in His mode as transcendent Ground of Being, the Self-Existent Nonexistence which forms the substract of Paraśakti’s activity. By way of conceptual exercise, then, we call Him tamasic.
It bears noting that there is no “sattvic” element to this image; for that, we must turn to Ardhanārīsvara, the “half-female Lord.” This is the re-unification of Śiva and Śakti at the level of the act of giving-forth the creation and reabsorbing the pure souls who climb back to their Source. It is in the sense of gracious mildness and benevolence that we may call this Form sattvic.
Of course, all of the observations of the last two paragraphs are symbolic in the lesser sense: they use the language of the dependent to point toward — for they are not capable of pointing immediately “to” — the essential. It can be very helpful to relate the processes of our immediate experience, of our own minds and bodies, to Transcendence, or temporal things to Eternity, but fanaticism and fundamentalism arise when we draw absolute conclusions from relative things.
Sattva, rajas, and tamas are the most basic processes — or, more precisely, tendencies — of Nature. None is either good or evil of itself. Yoga teachings, however, that only sattva tends toward openness, spontaneity, and peace. It is thus that we are taught to cultivate sattva in our individual economies. But Nature is, properly speaking, limited. She is the creation itself, and not the Creator. As the Scholastics, Hermeticists, and alchemists of the West know well, Nature is a living book; we may read her literally, morally, figuratively, or metaphysically, just like any true Scripture. But we must not mix up those senses; to do so is to stumble, and to persist is to fall into the abyss of reductionism, of solipsism, or of nihilism.