Material knowledge, any subject matter you can take, but that is temporary. Just like this body is temporary, similarly, any material knowledge you acquire, either you become a chemist or physicist or a medical man or an engineer, whatever you may acquire knowledge, all this knowledge will finish as soon as this body is finished. You forget. Death means forgetfulness.
Because the spirit does not die, eternal, so spiritual knowledge continues. If you develop spiritual knowledge... Suppose cent percent spiritual knowledge you acquire in this body. Then that will continue with you. Even after destruction of this body that spiritual knowledge will continue with you, and when you get next body, you begin... You finished your ten percent. You will begin again from eleven percent. That knowledge will not be lost. That is the law of nature. Spiritual knowledge... In the Bhagavad-gītā we have studied already, svalpam apy asya dharmasya trāyate mahato bhayāt. If you cultivate spiritual knowledge even one percent, two percent, that can render you greater service because it will continue. Once spiritual knowledge begun, it will not be stopped. The best thing is to finish it cent percent in this life because this human form of life is meant for cultivating spiritual knowledge.
It is not meant for material enjoyment. Material enjoyment means eating, sleeping, and defending and mating. These four principles, they are called material enjoyment. Just like we see advertisement. The other day I was seeing the New York Times magazine. So all advertisements were based on mating. That's all. So because mating is most attractive, therefore the shopkeepers, they advertise their dress, putting before one very nice girl. Because our attraction is for mating, so as soon as we see a nice girl our attention is diverted immediately. That is the psychology. So these are all material enjoyments: eating, sleeping, defending and mating.
And spiritual enjoyment is just opposite. There is no sense enjoyment. There is self-realization, or purifying the senses. Spiritual enjoyment means purifying the senses. Sarvopādhi-vinirmuktaṁ tat-paratvena nirmalam (CC Madhya 19.170). It is a purificatory process. And as soon as you purify your senses, then you become in full Kṛṣṇa consciousness and become eligible for being transferred to the spiritual world.
So this human form of life is specially meant for cultivation of spiritual knowledge. Because in any other form of life... There are eight million four-hundred-thousands of species of life, and the best developed consciousness form of life is the human form of life, especially civilized men. There are 400,000 species of human beings. Human being means with two hands and two legs. So not all of them are efficient, but they have got this Kṛṣṇa consciousness dormant. Even in the lowest aboriginal stage of life there is dormant Kṛṣṇa consciousness. But civilized life, Aryan, Aryan family, they are quite competent to deve..., culture, to cultivate this knowledge.
So jñāna, knowledge, means distinguishing between spirit and matter. And this knowledge should be cultivated and taken full advantage in this life. That is successful life. In the Śrīmad-Bhāgavatam it is stated, tasyaiva hetoḥ prayateta kovido na labhyate yad bhramatām upary adhaḥ (SB 1.5.18). Now, a living entity, a spiritual spark, is wandering, wandering from, not only from one country to another country or from one body to another, but one planet to another. The qualification of a living entity is called sarva-ga. Sarva-ga. Sarva means all, and ga means one can go. You can go anywhere.
Just like you have the facility of traveling over the surface of the world or in the outer space on the earth. But you cannot go beyond the orbit. This is called conditioned life. In conditioned life we are limited in our traveling. But in spiritual life you can travel anywhere. The best example is Nārada Muni. He can travel anywhere he likes. Even in this universe we have got a planet which is called Siddhaloka, a planet of the perfect. Not perfect completely, but they are called siddha. Siddha means almost perfect. The inhabitants of that planet, they can travel without any aid of a sputnik or aeroplane from one planet to another. We get this information from Śrīmad-Bhāgavata. So in spiritual life we have got complete freedom to move, to act, to enjoy. So that spiritual knowledge should be cultivated. That is the best utilization of this human form of life.
If we do not utilize this human form of life for spiritual cultivation, then we are practically committing suicide. Ātma-han.
There is a very nice Sanskrit verse that... Just like you have to cross a great ocean. Now, if you want to cross Atlantic Ocean from New York to England, then you must have a very nice ship and a good captain and the atmosphere very favorable. Then it is very easy to cross. So that example is given in a Sanskrit verse, nṛ-deham ādyaṁ su-labhaṁ su-kalpam. Now, to cross this ocean of material existence... This is ocean. It is compared with ocean. Bhava-sāgara. Sāgara means ocean. So to cross this ocean you have got very nice ship. What is that? Nṛ-deham. This human form of life. Nṛ-deham ādyam. It is very nice ship. And su-labhaṁ su-labhaṁ su-durlabham. Su-labham means this kind of ship you cannot get always. It is an opportunity.
This is an opportunity because we do not know what is going to happen in my next life. There is no guarantee that in next life you are going to take your birth in America or in human form of life. There is no guarantee. Therefore, so long you have got this opportunity, you must fully utilize it. Nṛ-deham ādyam su-labhaṁ su-durlabham. Su-labham, by opportunity, by fortune we have got this, su-labham. And su-durlabham. Su-durlabham means it is very difficult to get this body, because... Just imagine. By gradual evolutionary process from the aquatic to the plant life, then from plant life to worm life, then from worm life to bird's life, then from bird's life to beast life, from beast life to human life—this is the gradual process of evolution. So therefore this human form of life is very difficult to get. By some fortune you have got now. So therefore it is said, su-labhaṁ su-durlabham.
And you have got this nice ship. And guru-karṇa-dhāram. And if you have got a nice spiritual master who is captain, good captain, who can help you to ply your ship on the same. So nṛ-deham ādyam su-labhaṁ su-durlabham. And atmosphere is Kṛṣṇa consciousness, created by the Supreme Lord by delivering you the message of Bhagavad-gītā. So you have got very good atmosphere. Just you compare in the same way: If in Atlantic Ocean there is no wind, there is no hurricane, and you have got a very good ship and very good captain, now take this opportunity of crossing. If you don't cross, then you are committing suicide. Oh, very nice.
So these are the opportunities of developing your knowledge in Kṛṣṇa consciousness and spiritual culture. And the advantage is that as soon as you become fully conscious of your constitutional position, then you are freed from this material entanglement. This is called jñānam. Jñānam asammohaḥ. Don't be very hesitant. Asammohaḥ means if you want to acquire some knowledge, you should acquire it maybe slowly but acquire it very surely, step by step. Don't be impatient. Asammohaḥ. Not that blindly accepting something and thinking that "I have got all knowledge. Finished." No.
You have got developed consciousness, you have got intelligence, but that intelligence, consciousness, depends also on your mode of living, on your mode of behavior. Therefore one has to become a brāhmaṇa, sāttvika, in the modes of goodness. Then you will be patient, patient, śānta, peaceful. If you become hesitant, then you cannot. This is called asammohaḥ.