Rebirth

yonimanye prapadyante śarīratvāya dehinaḥ |

sthāṇumanye'nusamyanti yathākarma yathāśrutam ||2-2-7||

Some jīvas enter the womb for acquiring a body, while others assume a plant form

according to (their) karma and according to (their) thoughts.

This mantra is an important source of knowledge to know about rebirth. With regard to rebirth, śāstra is the primary means of knowledge, because there is no direct perception or scientific evidence for it. There might be supporting phenomena such as a person is born a prodigy and how everyone has different kinds of birth.

There are four factors that constitute a person; three bodies and ātmā. When an ignorant person dies, what happens to each factor? The physical body dies and it goes back to the five elements (pañca-bhūta). This is obvious through direct observation. However the subtle and causal bodies are not perceptible by any instrument of knowledge; we can only know from the śāstra. These two bodies survive the death of the physical body, and travel and occupy another physical body by entering the womb of a mother - yonimanye prapadyante śarīratvāya dehinaḥ. Some others enter the immobile body of a plant - sthāṇumanye'nusamyanti.

What is the factor that determines the birth of the jīva? yathākarma - based on what one has done in previous lives, the results determine what type of body one attains in the next life. The result of karma can only be exhausted by experiencing them, and experience is possible only through certain physical body, which is suitable for that experience. Therefore karma is the deciding factor for the type of birth. Similarly one’s birth is also yathāśrutam - based on one’s thought - what one dwells upon constantly (upāsanā). Whatever one thinks intensely is what one becomes. From thoughts, desire arises. From desires, action arises. From actions, habit is formed. From habits, character develops. And from characters, destiny emerges. Ultimately, our destiny begins with thought.