Attachment and aversion for the objects of the senses abide in the senses; let none come under their sway; for, they are his foes.
In simple words
Krishna identifies the real enemies: "Craving and hatred are built into every sense — they sit there waiting. Don't fall under their control. They are your real opponents."
Word-by-word meanings
इन्द्रियस्य इन्द्रियस्यof each senseअर्थेin the objectरागद्वेषौattachment and aversionव्यवस्थितौseatedतयोःof these twoनnotवशम्swayआगच्छेत्should come underतौthese twoहिverilyअस्यhisपरिपन्थिनौfoes
3.34 इन्द्रियस्य इन्द्रियस्य of each sense? अर्थे in the object? रागद्वेषौ attachment and aversion? व्यवस्थितौ seated? तयोः of these two? न not? वशम् sway? आगच्छेत् should come under? तौ these two? हि verily? अस्य his? परिपन्थिनौ foes.Commentary Each sense has got attraction for a pleasant object and aversion for a disagreeable object. If one can control these two currents? viz.? attachment and aversion? he will not come under the sway of these two currents. Here lies the scope for personal exertion or Purushartha. Nature which contains the sum total of ones Samskaras or the latent selfproductive impressions of the past actions of merit and demerit draws a man to its course through the two currents? attachment and aversion. If one can control these two currents? if he can rise above the sway of love and hate through discrimination and Vichara or right eniry? he can coner Nature and attain immortality and eternal bliss. He willl no longer be subject to his own nature now. One should always exert to free himself from attachment and aversion to the objects of the senses.
Contemporary scholarly and practical interpretations for modern seekers.
This interpretation draws on a specific tradition and may not represent the view of any single school. For authoritative guidance within a specific tradition, seek a qualified teacher.
Modern
In the previous verse, it was stated that even the learned person who studies the scriptures finds himself unable to live a life of high morality, because certain lower tendencies within him sometimes prove more powerful than his will. Merely prescribing a medicine that is unavailable everywhere does not constitute a cure for the disease. It is the duty of the philosopher and seeker of truth not only to reveal the weaknesses of our present life, but also to impart knowledge of the state of perfection and to show the path of practice through which we can become free from defects and establish ourselves in our complete nature. Only by doing this can such a philosopher and knower of truth fulfill the purpose of his generation.
It is true that every person acts according to their nature, but this nature is created by them through their own actions and thoughts, and not because of any external cause. Therefore, there is opportunity here for human effort. This is what Sri Krishna is explaining. In the mind of every person, attachment or aversion arises toward the objects of each sense. The objects of the senses—sound, touch, and so forth—cannot by themselves produce suffering or distraction in our inner consciousness. By grasping the objects, the mind develops attachment toward some and aversion toward others. Because of these attachments and aversions of the mind, the sight or attainment of pleasant or unpleasant objects brings joy or sorrow to the person. Having thus created attachment and aversion, the person then strives to gain what is pleasant and reject what is unpleasant. Because attachments and aversions constantly change with respect to objects, the mind remains perpetually disturbed. Sri Krishna says that these attachments and aversions are thieves that rob the mind of peace, and because of them, a person cannot live a true life. This is indeed a matter of sorrow.
After revealing the actual state of things, the Lord instructs all seekers that a person should not be enslaved by these two forces.
The Bhagavad Gita nowhere teaches escape from the external world, either directly or indirectly. The Lord's teaching here is to live in the present circumstances of life, experiencing all experiences through the body, mind, and intellect. The insistence is only that in all circumstances, a person should remain the master of the mind and other instruments, and not become their servant. The means to attain such mastery is to become free from attachment and aversion.
To gain freedom from attachment and aversion, one must eliminate false ego and the other tendencies arising from it, because attachment and aversion are connected to ego. Therefore, when actions are performed without ego, desires are destroyed. Desires give rise to the mind, and there the play of ego occurs. As desires gradually diminish, the mind is also destroyed. When the mind is destroyed, the ego—which is the reflection of the pure atman—is also destroyed.
The Lord explains the means to destroy desires in the following verse.