Dhyāna Dhāraṇā · Dhāraṇā 15
पिण्डमन्त्रस्य सर्वस्य स्थूलवर्णक्रमेण तु । अर्धेन्दुबिन्दुनादान्तशून्यैतैर्ध्यानमुत्तमम् ॥
piṇḍamantrasya sarvasya sthūlavarṇakrameṇa tu | ardhendu-bindu-nādānta-śūnyaitair dhyānam uttamam ||
Of any compact mantra, following the sequence of gross letters — half-moon, point, final resonance, void — with these, supreme meditation.
Fifteenth dhāraṇā. Technique of meditation upon the subtle parts of the mantra. Every mantra has a structure going from gross (sthūla) to subtle. The letters are the gross level. Beyond them lie: ardhendu (the half-moon), bindu (the point), nāda (the resonance), anta (the end), śūnya (the void).
Each level is subtler than the previous. The half-moon is the vibration that follows pronunciation. The bindu is the point of concentration where sound condenses. The nāda is the resonance that remains after. And śūnya is the absolute silence where everything dissolves.
Dhyānam uttamam — supreme meditation. You do not meditate upon the meaning of the mantra. You meditate upon its progressive dissolution from audible sound to silence. The mantra is used as a vehicle to reach the void that precedes and follows it.