“How is the material nature controlling? She has a machine made of the three modes of nature. Karanam guna-sango ‘sya sad-asad-yoni-janmasu [Bg. 13.22]. People are contacting these three modes of nature and thus being “infected”. We know that if we contract some disease, knowingly or unknowingly, that disease will develop. This is the law of nature. Even if you do not know when or how you contracted a particular disease, which is no excuse. You must suffer.
Similarly, there are three modes of material nature one can become “infected” by – goodness, passion, and ignorance. Not knowing about this is no excuse. If in the law court you say “Your Honor, I did not know I would be punished for stealing, “the magistrate or judge will not excuse you. And if the government law is strict, you can imagine how strict the stringent laws of material nature are.
Knowingly or unknowingly, in this life we are being infected by a particular combination of the modes of material nature and thus creating our next body. There are 8,400,000 different varieties of life forms. Why? The answer is in the Bhagavad-gita: karanam guna-sangah. There are so many different species of life because each living entity is becoming infected with a particular combination of the qualities of material nature. This is going on perpetually. “Perpetually” means we do not know when this process began or when it will end. Therefore we say it is perpetual.
In this human form of life we have the great advantage of being able to study all these things – what is the living entity, how he is being infected by material nature, and how he is taking different bodies. The first thing we must understand is that we are not the body. Therefore in the very beginning of the Bhagavad-gita Lord Krishna tries to impress upon us that we are not this body but rather the owner or occupier of the body. This is His first instruction. If we understand this instruction we can rise above the bodily platform.”
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Quest for Enlightenment”, Page 68