Patanjali Yoga Sutra 2.50

Sanskrit Sutra

बाह्याभ्यन्तरस्तम्भवृत्तिः देशकालसंख्याभिः परिदृष्टो दीर्घसूक्षमः॥५०॥

Swami Vivekananda's translation

Its modifications are either external or internal, or motionless, regulated by place, time, and number, either long or short.

Vyasa Bhashya (Sanskrit)

बाह्याभ्यन्तरस्तम्भवृत्तिर्देशकालसंख्याभिः परिदृष्टो दीर्घसूक्ष्मः ॥ ५० ॥

यत्र प्रश्वासपूर्वको गत्यभावः स बाह्यः। यत्र श्वासपूर्वको गत्यभावः स आभ्यन्तरः। तृतीयः स्तम्भवृत्तिर्यत्रोभयाभावः सकृत्प्रयत्नाद्भवति। यथा तप्ते न्यस्तमुपले जलं सर्वतः संकोचमापद्यते तथा द्वयोर्युगपद्गत्यभाव इति। त्रयोऽप्येते देशेन परिदृष्टा इयानस्य विषयो देश इति। कालेन परिदृष्टाः क्षणानामियत्तावधारणेनावच्छिन्ना इत्यर्थः। संख्याभिः परिदृष्टा एतावद्भिः श्वासप्रश्वासैः प्रथम उद्धातस्तद्वन्निगृहीतस्यैतावद्भिर्द्वितीय उद्धात एवं तृतीयः। एवं मृदुरेवं मध्य एवं तीव्र इति संख्यापरिदृष्टः। स खल्वयमेवमभ्यस्तो दीर्घसूक्ष्मः ॥ ५० ॥

Vyasa Bhashya (English Translation)

Where the cessation of motion is preceded by exhalation, it is the external (bahya) modification. Where the cessation of motion is preceded by inhalation, it is the internal (abhyantara) modification. The third is the suspended modification (stambha-vritti), where the absence of both (inhalation and exhalation) occurs through a single effort. Just as water thrown onto a hot stone shrinks from all sides at once, similarly there is a simultaneous cessation of both movements.

All three of these are regulated by place (desha) — their sphere of influence is of such an extent. They are regulated by time (kala) — meaning they are defined by the measurement of the number of moments (kshanas). They are regulated by number (sankhya) — meaning, by so many inhalations and exhalations is the first udghata (impulse); for one who has thus controlled it, by so many is the second udghata; and similarly the third. Thus it is mild, thus it is medium, and thus it is intense; this is how it is regulated by number. Thus practiced, it indeed becomes prolonged (dirgha) and subtle (sukshma). || 50 ||

Chapter link: Yoga Sutra Chapter 2