In the Gita you will find: "Even the man of knowledge acts in conformity with his own nature; beings follow nature; what shall restraint avail." Ch. III-33.
The meaning of this Sloka is misunderstood by many people. Many have become fatalists. They lead a life of inertia. They say: "What is the use of our exertion? Nature is all-in-all. We cannot go against nature? Nature is irresistible. All living beings follow their own nature. There is influence of man's nature on his conduct. What can coercion and inhibition do? Let us not exert ourselves." This is a sad mistake. It is a lamentable misapprehension.
There is a clear solution for this in the next Sloka 34. Slokas 33 and 34 should go together. Then the meaning is quite clear. Even the man of knowledge or a Jnani behaves according to his own nature. It needs no saying that a man of ignorance acts according to his own nature, because he does not know how to control it. If every individual behaves according to his own nature only, if there is none who has no nature of his own, then there is no scope for individual exertion (Purushartha). In that case the teachings of the Sastras which inspire people to right exertion would be quite purposeless.
In the next verse Lord Krishna asks Arjuna to do Purushartha, to go above Raga Dvesha, the two currents of attraction and repulsion. "Affection and aversion for the objects of the senses abide in the senses; let none come under the dominion of these two; they are the destroyers of the path." Ch.III-34. If the aspirant has controlled these two Vrittis, he has already conquered Nature, he has become the lord of Nature. He can command Nature. Nature has become his obedient servant. Nature operates through these two Vrittis. What you call the universe is only Raga Dvesha. There is no world for that Jnani or Yogi who has subdued these two Vrittis. There is no world apart from these two Vrittis. Man is bound or attached to sensual objects through the Vritti, Raga. When he develops Vairagya, Raga is annihilated. An ignorant man is a slave of these two Vrittis and so he is tossed about hither and thither like a straw in this ocean of Samsara. Patanjali Maharishi prescribes easy definite methods in his Raja Yoga philosophy to control these two Vrittis. His definition of Yoga is:
YOGAH CHITTA VRITTI NIRODHAH
"Yoga is control or restraint of the modifications of the Chitta."
He also prescribes Purushartha to extirpate Vrittis and control nature and to attain Kaivalya Moksha or independence. He does not say: "Nature is very powerful, keep quiet and become a slave of nature. What is the use of your struggle and Sadhana?" His Yoga is an exact science. He prescribes definite, positive, accurate and effective methods to control nature. He says: "Control the Vrittis and then rest in your own Svarupa (essence). The whole nature is under your control." Vasishtha also asks Sri Rama to do Purushartha.
Through Raga a man loves an object; through Dvesha he dislikes an object. If anyone rises above the sway of likes and dislikes, love and hatred, affection and aversion, he is no longer subject to his nature. He can understand the teachings of the Sastras. His mind is pure. If he becomes a victim of these two currents, his mind becomes impure. He cannot understand the significance of the Sastras. He neglects his own duties. He begins to do the duties of others as his mind is in a state of confusion and bewilderment. Raga Dvesha are great obstacles in the spiritual path. They are the adversaries of a man or aspirant. They are like robbers on the highway. If Viveka and Vichara (discrimination and enquiry of the nature of the Atman) dawn in the aspirant, Raga Dvesha will take to their heels.
O man! Learn practical lessons from Nature. The mango tree does Purushartha. It gives shade to the weary traveller and delicious fruit to the proprietor. The jasmine emanates sweet fragrance to all. The ants are busy with collecting grains in summer. They enjoy the grain in their holes during the rainy season and in winter. The bees collect honey vigorously from the flowers and get intoxicated with joy drinking honey. The rivers supply good sparkling water to people. The sun gives energy and warmth to plants and human beings and converts saltish waters of the sea into good drinkable water. The sandal tree sends out fragrance in all directions. The musk-deer gives musk. The earth supplies grains, gold, iron, lead, vegetables and other necessities to man. The parents prescribe Purushartha to their children. The teachers ask the student: "Study well, have a good character. Pass in your examination and get a good job. Do charity, control the senses and become a good man."
You will find in the Gita: "But the disciplined self, moving among sense-objects with senses free from attraction and repulsion, mastered by the self, goeth to peace." Ch. II-64. The difficulty that you encountered in Sloka 33 is now obviated. Do Purushartha now. Remove Raga Dvesha and rest in peace. Then Nature becomes your obedient servant. You are the master or lord of Nature. Do Sadhana. Practise! Practise! Realise! Realise! This is your highest duty. You have taken this body to achieve this end!