Praṇava-Māhātmya and the Twofold Mantra (Sūkṣma–Sthūla) in Śaiva Sādhanā
तदर्वाग्बिंदुरूपं हि नादरूपं तदुत्तरम् । तदर्वाक्कर्मलोकस्तु तदूर्ध्वं ज्ञानलोककः
tadarvāgbiṃdurūpaṃ hi nādarūpaṃ taduttaram | tadarvākkarmalokastu tadūrdhvaṃ jñānalokakaḥ
Below that is indeed the realm in the form of Bindu, and above it is the realm in the form of Nāda. Below lies the world of action (karma-loka), while above is the world of knowledge (jñāna-loka).
Suta Goswami
Tattva Level: pasha
Shiva Form: Sadāśiva
Role: teaching
It outlines a Shaiva hierarchy of inner and cosmic planes: karma (action-bound living) is lower, while jñāna (liberating insight) is higher, with Bindu and Nāda indicating subtle spiritual principles leading the seeker toward Shiva-realization.
The Linga is presented in Shaiva thought as a bridge from the manifest to the subtle: devotion and ritual (karma) mature into inner contemplation of Nāda-Bindu, culminating in knowledge (jñāna) that reveals Shiva as the supreme Pati beyond bondage.
Move from outer karma to inner japa and dhyāna: repeat the Panchākṣarī (Om Namaḥ Śivāya) with steady breath-awareness, listening inwardly to nāda and concentrating the mind into bindu-like one-pointedness.