In plain words
cannot but arise. 'Inhalation and exhalation are the jīva's Prakṛti' -- what does that mean? 'These are natural to living beings' is one such answer.
Based on an answer of this kind, whether one calls the sense of these words 'Prakṛti', 'svabhāva' or 'naisargika', or calls it 'ignorance', the meaning is one and the same. The truth is that I myself do not even know about my own breath. Yogis, who by the strength of the mind stop the movement of the nāḍīs and the pulsation of the heart, can make it visible to us that the undertaking of an act is signalled by volition alone. Karma is not something that flaps about baselessly in the air. Unless we ourselves become agents, the workings of karma do not set out at all. 'Na jāti, icchati, yatate' -- this is a Nyāya-śāstra sūtra. Following one's own knowledge, desire arises; and following that desire, it comes to pass that one performs karma. 'What one contemplates, that one desires; what one desires, that one does; what one does, that one becomes' -- this is a Vedānta sūtra. Whatever one contemplates in the mind, that one comes to desire. Following that desire, one performs karma. Following what one has done, one obtains accordingly. A person's very nature as a personality is made of desire. According to what one desires, one resolves; following that resolve, one performs karma; and following that karma, one creates oneself. That is, following one's own Buddhi, one brings upon oneself one's own birth. This very Buddhi is what is called Prakṛti; therefore, if one comes to know that one's own Buddhi is the maker of Prakṛti, one may see to getting free of that Prakṛti.
It may be understood either that the jīva is subject to Prakṛti, or that the jīva is seated within Prakṛti. Leaving aside for now the matter of karma in the science that carries such profound meanings, it is necessary to know a little also about the karma that is unreachable to, and unrelated to, the ordinary intellect of human beings.