Bhagavad Gita 13.21कार्यकारणकर्तृत्वे हेतुः प्रकृतिरुच्यते।पुरुषः सुखदुःखानां भोक्तृत्वे हेतुरुच्यते ॥

Pleasure and pain are the fruits of virtuous and vicious actions. The force of desire acts on the mind and the mind impels the senses to act to get the objects of desire. Good and evil actions proceed from Nature and lead to happiness or misery. Evil actions produce misery and sorrow. Virtuous actions cause happiness and joy. The soul is the enjoyer. The wife works and prepares nice, palatable dishes the huand silently enjoys the fruits of her labour. He sits quietly and eats them to his hearts content. Even so Nature works and the soul experiences the fruits of Her labour, viz., pleasure and pain.When harmony predominates, virtuous actions are performed. When there is a preponderance of Rajas, both virtuous and vicious actions are performed. When Tamas predominates, sinful, unlawful and unrighteous actions are done.In the place of Kaarana (कारण) which means cause, some read Karana (करण) which means instrument such as the five organs of knowledge, five organs of action, mind, intellect and egoism (thirteen principles located in the body).Karya The effect, viz., the physical body. The five elements which form the body and the five senses, and which form the senseobjects which are born of Nature come under the term effect