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.