The first page of my forthcoming book, The Recognition Sūtras: A translation and explanation of 'The Heart of the Teachings on the Recognition of Oneself as God' (Pratyabhijñā-hṛdayam):
On the inner meaning of Oṃ namaḥ shivāya
Oṃ namaḥ śivāya satataṃ pañca-kṛtya-vidhāyine |
cidānanda-ghana-svātma-paramārthāvabhāsine || 1 ||
Yes! Reverence to the Divine, who constantly performs the five Acts (of creation, preservation, reabsorption, concealment, and revelation)—and who, by so doing, reveals the ultimate reality of one’s own Self, which is nothing but the Joy of Awareness.
Kṣemarāja begins his work with the auspicious word namas, “reverence,” “obeisance,” or “homage,” from the root nam, “bow.” To bow is the beginning and the ending of the spiritual path. It is to humble oneself, to acknowledge the infinite majesty of the Divine. It is awe in the face of the great mystery. It is the recognition that one’s mind, with all its power, is merely the most ephemeral and fleeting expression of the one Consciousness that pervades all of reality (this is why we lower the head when we bow). That divine Consciousness is the object of Kṣema’s devotion: namaḥ śivāya, “reverence to Śiva.” In his tradition of nondual Śaiva Tantra, the name Śiva (lit., “benevolent”) denotes the single all-pervasive divine Awareness that is both the ground and substance of the whole of reality.
Kṣemarāja is a nondualist, therefore he holds that Śiva constitutes the essential nature of every conscious being. In this view, there is no “other” to bow to, so Kṣema understands namaḥ śivāya to mean “I merge my awareness in my Divine nature.” He takes namas to be equivalent to the word samāveśa, which in Śaiva Tantra denotes the experience of oneness with the Absolute, or more accurately the experience of sharing a single Self with God. (This experience is thought to arise due to the temporary falling away of one’s false identification with the limited body-mind, which obscures the true reality of oneness.) Arguing for the equivalence of these two terms, namas and samāveśa, is not such a stretch, for what greater act of reverence is there than to merge oneself with the object of one’s devotion? What greater act of humility than to dissolve one’s sense of separateness? What greater obeisance than acknowledging that only the Divine truly exists? Such obeisance is the release of all that holds you back from falling into the very Heart of your essence-nature.
Try it now. Whisper softly to yourself, “Oṃ namaḥ śivāya. I allow my awareness to merge into my real divine nature.” Take a deep breath, and let yourself open to the sacred core of your being. Quietly treasure the barest glimpse of it, yet don’t make a big deal out of it. The moment the experience is no longer fresh, let it go and return to the book.
 Namaḥ is a form of the word namas (as in namaste).