तत्र तं बुद्धिसंयोगं लभते पौर्वदेहिकम् |
यतते च ततो भूय: संसिद्धौ कुरुनन्दन || 43||
tatra taṁ buddhi-sanyogaṁ labhate paurva-dehikam
yatate cha tato bhūyaḥ sansiddhau kuru-nandana
tatra—there; tam—that; buddhi-sanyogam—reawaken their wisdom; labhate—obtains; paurva-dehikam—from the previous lives; yatate—strives; cha—and; tataḥ—thereafter; bhūyaḥ—again; sansiddhau—for perfection; kuru-nandana—Arjun, descendant of the Kurus
There he comes in touch with the knowledge acquired in his former body, O son of the Kurus, and strives still further for perfection.
The theory of reincarnation is explained in greater detail here. Though the body is dead and gone, yet the mind, with all the impressions acquired in previous births, live on, and when the Jiva takes another body, the former mental endowment comes to him. So he continues the sadhana exactly from the point where it came to an end when the body fell. Nothing is lost in death except the fleshy tabernacle. There is a continuity from birth to birth, and the chain continues till the moment when liberation is attained, and the mind with all its samskaras is destroyed. This view of rebirth is the only possible explanation for the disparity in the mental make-up of different individuals as we see them. The good thoughts, feelings, and actions of the past create a natural propensity for good things in this life. Even so, the bad thoughts and deeds done in the past produce a natural inclination to evil in this life. So, it is a warning to all to be careful of what force they are generating at the present moment. They should realise that they are accumulating samskaras and giving a special direction to their future life by their thoughts and actions at the present moment. Let no one complain that he is bad because society or circumstances made him bad. He has himself created the bad in and around him, and he should shoulder full responsibility for what he is in the present birth. He is the maker of his own destiny. He reaps what he sows.
From this, we understand that good and bad, knowledge and ignorance follow every being like his shadow from birth to birth. When the entire karma is destroyed in the fire of Jnana, then there is no more any shadow because there is no more any separate individual as such. So even before the body falls, man should enlighten his intellect and give it perfect knowledge. By several kinds of spiritual practices, he should instill divine tendencies. Those alone follow man after death. All other things, the dearest and the most precious are left behind. The wise man should therefore purify the subtle body and instill divine flavour and knowledge. As nothing that is done goes to waste, the little japa, tapas, knowledge. Dana and Dharma, will bear fruit in the next life and make the spiritual journey easier and quicker.
Swami Vivekananda Says —
But though it is so hard to reach the goal, yet even our smallest attempts are not in vain. We know that nothing is lost. In the Gita, Arjuna asks Krishna (*), “Those who fail in attaining perfection in yoga in this life, are they destroyed like the clouds of summer?” Krishna replies, “Nothing, my friend, is lost in this world. Whatever one does, that remains as one’s own, and if the fruition of yoga does not come in this life, one takes it up again in the next birth.” Otherwise, how do you explain the marvellous childhood of Jesus, Buddha, Shankara?[Source]
Question: Being born in the family of yogis what should man do?
Answer: He should complete and bring to perfection the yogic practice which he kept unfinished in the previous birth.
Question: How does he acquire yogic samskara from the moment of birth?
Answer: His past sadhana preserved in the mind is reborn with him, and so he obtains it as his natural endowment.