The Lord then explained that within this brahmāṇḍa, or universe, there are innumerable living entities who, according to their own fruitive activities, are transmigrating from one species of life to another and from one planet to another. In this way their encagement in material existence has continued since time immemorial. In actuality, these living entities are atomic parts and parcels of the Supreme Spirit. It is said in the Śvetāśvatara Upaniṣad Śrīmad-Bhāgavatamthat the length and breadth of the individual soul is 1/10,000th part of the tip of a hair. The atomic magnitude of the living entity is confirmed in the Eleventh Canto of Śrīmad-Bhāgavatam (11.16.11). And in the Tenth Canto (10.87.30) Sanandana-kumāra, while performing a great sacrifice, quotes the following statement by the personified Vedas: "O Supreme Truth! If the living entities were not infinitesimal sparks of the Supreme Spirit, each minute spark would be all-pervading and could not be controlled by a superior power. But if the living entity is accepted as a minute part and parcel of the Supreme Lord, one can automatically understand how he is controlled by the supreme power. The latter is his actual constitutional position, and if he remains in this position he can attain full freedom. If one mistakenly considers his constitutional position equal to that of the Supreme Personality of Godhead, he becomes contaminated by the doctrine of nonduality and his efforts in transcendental life are rendered ineffective."
Lord Caitanya continued His teachings by pointing out that there are two kinds of living entities, the eternally liberated and the eternally conditioned. The eternally conditioned living entities can be divided into two types, the moving and the nonmoving. Those that remain in one place—trees, for example—are classified as sthāvara, or nonmoving entities, and those that move—such as birds and beasts—are called jaṅgama, or moving entities. The moving entities are further divided into three categories: those that fly in the sky, those that swim in the water, and those that walk on land. Out of the many millions and trillions of living entities on land, human beings are very few. Out of that small number of human beings, most are totally ignorant of the spiritual science, are unclean in their habits, and have no faith in the existence of the Supreme Personality of Godhead. In short, most human beings live like animals. Therefore these can be deducted from the number of human beings that constitute civilized human society.
We can hardly find any human beings who believe in the Vedic scriptures and the existence of God, or even in proper behavior. Those who do believe in these things, and in advancing in spiritual life, are known as Āryans. Out of those who believe in the scriptures and the advancement of human civilization, there are two classes—the righteous and the unrighteous. Those who are righteous generally execute fruitive activities to derive some good result for sense gratification. Out of many such persons who engage in righteous activities for sense gratification, only a few come to know about the Absolute Truth. These are called jñānīs, empiric philosophers in search of the Absolute Truth. Out of many hundreds and thousands of such empiric philosophers, only a handful actually attain liberation. When one is liberated, he theoretically understands that the living entity is not composed of material elements but is spirit soul, distinct from matter. Simply by understanding this doctrine, even theoretically, one qualifies as a mukta, or liberated soul. But the actual mukta is he who understands his constitutional position as part and parcel of the Lord and as His eternal servant. Such liberated souls engage with faith and devotion in the service of the Lord, and they are called kṛṣṇa-bhaktas, or Kṛṣṇa conscious persons.
Kṛṣṇa-bhaktas are free from all material desires. Although those who are theoretically liberated by knowing that the living entity is not material may be classified among liberated souls, they still have desires. Their main desire is to become one with the Supreme Personality of Godhead. Such persons are very much attached to performing Vedic rituals and righteous activities in order to enjoy material prosperity. Even when some of them transcend material enjoyment, they still try to enjoy in the spiritual world by merging into the existence of the Supreme Lord. Some of them also desire to attain mystic powers through the execution of yoga. As long as any of these desires are within a person's heart, he cannot understand the nature of pure devotional service, and on account of constantly being agitated by such desires, he is not peaceful. Indeed, as long as there is any desire for material perfection at all, one cannot be at peace. Since the devotees of Lord Kṛṣṇa do not desire anything material, they are the only peaceful persons within this material world.