Sankhya Yoga 2.31

 Verse 2.31 One must not deviate from his Swadharma (one’s own duty)

स्वधर्ममपि चावेक्ष्य न विकम्पितुमर्हसि |

धर्म्याद्धि युद्धाच्छ्रेयोऽन्यत्क्षत्रियस्य न विद्यते || 31||

swa-dharmam api chāvekṣhya na vikampitum arhasi

dharmyāddhi yuddhāch chhreyo ’nyat kṣhatriyasya na vidyate

swa-dharmam—one’s duty in accordance with dharma; api—also; cha—and; avekṣhya—considering; na—not; vikampitum—to waver; arhasi—should; dharmyāt—for righteousness; hi—indeed; yuddhāt—than fighting; śhreyaḥ—better; anyat—another; kṣhatriyasya—of a warrior; na—not; vidyate—exists

Besides, considering your duty, you should not waver. Indeed, for a kshatriya, there is no better engagement than fighting for upholding righteousness.

From this verse onwards, Krishna talks about the absolute necessity of fulfilling one’s own duty. This is called swadharma. Dharma is of two kinds. Samanya dharma and visesha dharma or swadharma. Samanya Dharma is common to one and all. The examples of Samanya Dharma are cleanliness, non-violence, speaking truth etc.

But the vishesha dharma or swadharma changes from time to time and person to person. In our culture, a person’s life is divided into four ashramas, parts namely Brahmacharya, Grihasta, Vanaprastha and Sanyasa. The person has duties to fulfill in each of these ashramas. In Brahmacharya ashrama, which lies in the first twenty four years of one’s life, one has to dedicate his time for studies. He is not supposed to earn money for himself during this period. He should lead a simple lifestyle and serve his parents and teacher. Next comes Grihastha ashram in which a person marries and leads a family life. During this stage, he will work and earn to sustain his family. He is allowed to enjoy family life provided he attains them through proper and rightful means. The primary duty of a grihastha is to look after his family, raise children and help those around him. It is the duty of a grihastha to take care of people from other ashramas since they do not work to earn their means. After fulfilling the duties of grihastha a person enters vanaprastha. The word literally means living in the forest. The couple leave all their responsibilities to their grown up children who now are in their grihastha stage and choose to live a life of seclusion. They would dedicate their entire time for the study of shastra. Once their study is over, the couple either part or live under the same roof not as a couple but as two sanyasis. This sanyasa ashrama is the final stage of one’s life. The person spends his entire time in meditation and contemplation of the higher truth and lives until his prarabdha continues. 

Based on the vision of shastra, people are divided into four categories, not by birth but by their profession and nature (gunas). The four (varnas) categories are brahmana, kshatriya, vaishya and shudra.

These are not only not based on people’s birth but no category is higher or none is lower to the other three. Each one has its place in the scheme of things. It is just that by nature each one chooses a different profession. A brhamana’s job is to learn and teach and not earn money for his living. A kshatriya’s job is to protect and save, a vaishya’s job is to run businesses and create wealth and a shudra’s job is to work and serve. One will be in any of these professions irrespective of the caste he is born into. Even children of the same parents could differ in their varnas based on their nature. Within the family one might choose to be a teacher while one might do business, hence it is possible to have a brahmana and a shudra within the same family based on their nature and chosen profession.

Once one has chosen a profession, he needs to adhere to all the guidelines for that varna. Here Arjuna is a kshatriya. As a kshatriya, Arjuna’s duty is to protect the dharma by fighting against Duryodhana. Krishna says if you consider swadharma of a kshatriya, which is protecting his own people by fighting enemies, there is no better engagement than the war that has come about.