Bhagavad Gita, Chapter 13, Verse 20

कार्यकारणकर्तृत्वे हेतुः प्रकृतिरुच्यते । पुरुषः सुखदुःखानां भोक्तृत्वे हेतुरुच्यते

kāryakāraṇakartṛtve hetuḥ prakṛtirucyate | puruṣaḥ sukhaduḥkhānāṃ bhoktṛtve heturucyate

Translation

As the producer of the effect and the instruments, Prakṛti is said to be the cause; as experiencing pleasure and pain, Puruṣa is said to be the cause.

— Alladi Mahadeva Sastri

Word meanings

kāryakāraṇakartṛtve

of acts, and, of causes, and, in the creativeness

hetuḥ

the cause

prakṛtiḥ

matter

ucyate

is called

puruṣaḥ

spirit

sukhaduḥkhānām

of pleasures, and, of pains, and

bhoktṛtve

in the enjoyingness

hetuḥ

the cause

ucyate

is called

Śaṅkarācārya's commentary

The effect (kārya) is the physical body, and the instruments (karaṇas) are the thirteen located in the body (five organs of sensation, five of activity, manas, buddhi, and ahaṃkāra). The five elements (bhūtas) which build up the body, and the five sense-objects, are included under the term 'effect.' All qualities, such as pleasure, pain and delusion, which are born of Prakṛti, are included under the term 'instruments,' since those qualities are seated in the instruments, the senses. In the production of the physical body, of the senses and their sensations, Prakṛti is said to be the cause; as such, Prakṛti is the cause of saṃsāra. Puruṣa, Jīva, Kṣetrajña, the Enjoyer (Bhoktṛ) — all synonymous — is said to be the cause as perceiving pleasure, pain, and other objects of experience. When there is a conjunction — in the form of avidyā — of Puruṣa, the experiencer, with Prakṛti, the object of experience, then only is saṃsāra possible.