There are three kinds of departmental study in the Vedas. First thing is sambandha. Sambandha means "What is my relationship with God." This is stated there. In the Vedānta it says, janmādy asya yataḥ. The Absolute Truth is that from whom everything is generated. So everything, amongst everything, I am also, you are also. So you are also coming from that Supreme Absolute Truth. Kṛṣṇa says, mamaivāṁśo jīva-bhūtaḥ: (BG 15.7) "All these living entities..." Sarva-yoniṣu kaunteya: (BG 14.4) "In any species, any form of life..." Sambhavanti mūrtayo yāḥ: "As many forms are there..." Not only human beings, the animals, the trees, the birds, the aquatics, the insects, everyone, all living entities. Kṛṣṇa says, sarva-yoniṣu kaunteya sambhavanti mūrtayo yāḥ: "In any species of life, as many forms are there," ahaṁ bīja-pradaḥ pitā, "I am their original father." Bīja-pradaḥ pitā, seed-giving father. So as father places the seeds within the womb of the mother, similarly the material nature is the mother and Kṛṣṇa is the father. The Kṛṣṇa impregnates the material nature, and we come out in different forms. Sveda-ja, pādapa-ja and jarāyu-ja, and aṇḍa-ja. Sveda-ja means by perspiration, through perspiration. Just like bed bugs. Bed bug... Because if you keep your bed nasty, do not keep it very clean, then by your perspiration, there is generation of these bed bugs. They are called sveda-ja, by perspiration. And aṇḍa-ja, through the eggs. Just like the birds, the living entity is coming through the eggs. That is called aṇḍa-ja. Sveda-ja, aṇḍa-ja, jarāyu-ja. Embryo. Just like we are coming from the embryo. Aṇḍa-ja, then jarāyu-ja. And pādapa-ja, coming from the seeds, the trees, plants. So within these four groups, all different living entities are coming.
So the..., by gradual evolution, we are coming to the human form of life. So in the human form of life, here there is a prerogative, there is a chance to know what is God and what is my relationship with Him. That is called sambandha-jñāna.