Yoga Sūtra Chapter Two verse 50

बाह्याभ्यन्तरस्थम्भ वृत्तिः देशकालसन्ख्याभिः परिदृष्टो दीर्घसूक्ष्मः ॥५०॥

bāhya-ābhyantara-stambha-vṛttiḥ deṣa-kāla-saṃkhyābhiḥ paridṛṣṭaḥ dīrgha-sūkṣmaḥ ||50||

The external, internal and suspension fluctuations
are seen to be long and subtle
through place, time and number.

bāhya - externalābhyantara - internalstambha - suspensionvṛtti - fluctuation; modification; turning; set in motion, course of action, behaviour, movement; activity, function; professiondeśa - placekāla - time, a period of time; season, the proper time or season forsāṃkhya - enumeration; a numberparidṛṣṭa - seen to bedīrgha - long, for a long time; a long vowelsūkṣma - subtle; atomic; intangible

Commentaries and Reflections

Commentary by Paul Harvey:

Some Prāṇāyāma Techniques prioritise Length.
Other Prāṇāyāma Techniques prioritise Subtlety.
While yet other Prāṇāyāma Techniques prioritise Both.
– Reflection on Yoga Sūtra Chapter Two verse 50