Therefore, in the śāstras it is advised, acintyāḥ khalu ye bhāvā na tāṁs tarkeṇa yojayet. Acintyāḥ khalu ye bhāvāḥ. Things which are beyond your perception, sense perception, acintya, mental speculation, not cintanīya... Acintya. Acintya means mentally speculating. Beyond that, acintya, you cannot think of how this pealike form develops into such a big brain or small brain. The hands, legs, and the mechanical process of different body... This is a machine. In the material world we manufacture machine, manufacturing different parts and assembling them. (aside:) The child may be... But this machine is automatically developing. There is no question of manufacturing each part and then assembling. It is yantra. This body is yantra, machine. That is stated in the Bhagavad-gītā:
- īśvaraḥ sarva-bhūtānāṁ
- hṛd-deśe 'rjuna tiṣṭhati
- bhrāmayan sarva-bhūtāni
- yantrārūḍhāni māyayā
- (BG 18.61)
Īśvara, the Supreme Personality of Godhead, is situated in everyone's heart. He is supervising what kind of yantra, or machine, this living entity requires for fulfilling his desires. That is karma. He is engaged in such karma, and he is manufacturing by his karma another body. Everything is going on by the laws of nature. Prakṛteḥ kriyamāṇāni guṇaiḥ karmāṇi sarvaśaḥ (BG 3.27). Guṇaiḥ. By different guṇas—sattva-guṇa, rajo-guṇa, tamo-guṇa, goodness, passion, and ignorance—very subtle machineries are going on. They are all material.
So here it is said, therefore, dravya-sphuraṇa-vijñānam. Dravya means physical. Dravya-jñāna. Dravya-jñāna means physical knowledge. And brahma-jñāna means spiritual knowledge. So here it is said, dravya-sphuraṇa. The material, physical, phenomenal atmosphere is developing one after another. The medical science, they are trying to study different cells; but wherefrom the cells came into action? That is by the influence or by the manipulation of prakṛti. Prakṛteḥ kriyamāṇāni (BG 3.27). And prakṛti is working under the direction of Supreme Lord, Kṛṣṇa. Mayādhyakṣeṇa prakṛtiḥ (BG 9.10). Therefore, ultimately, by the superintendence of the Supreme Personality of Godhead everything is going on. But how it is going on, that we cannot explain. We have got limited knowledge. Therefore śāstra says, "Don't try to speculate, because you are imperfect, but things are going on like this." Try to understand. Acintyāḥ khalu ye bhāvā na tāṁs tarkeṇa yo... Simply by your so-called argument and logic you cannot understand. You have to hear from the authorities that "Things are going on like this."