There are three classes of intelligent living beings within this world.
“According to Śrīla Madhvācārya there are three classes of intelligent living beings within this world, namely the demigods, ordinary human beings, and demons. A living being endowed with all auspicious qualities — in other words, a highly advanced devotee of the Lord — either on the earth or in the higher planetary systems is called a deva, or demigod. Ordinary human beings generally have good and bad qualities, and according to this mixture they enjoy and suffer on the earth. But those who are distinguished by their absence of good qualities and who are always inimical to pious life and the devotional service of the Lord are called asuras, or demons.
Of these three classes, the ordinary human beings and demons are terribly afflicted by birth, death and hunger, whereas the godly persons, the demigods, are aloof from such bodily distress. The demigods remain aloof from such distress because they are enjoying the results of their pious activities; by the laws of karma, they are unaware of the gross suffering of the material world. As the Lord says in Bhagavad-gītā (9.20):
trai-vidyā māṁ soma-pāḥ pūta-pāpā yajñair iṣṭvā svar-gatiṁ prārthyante
te puṇyam āsādya surendra-lokam aśnanti divyān divi deva-bhogān
“Those who study the Vedas and drink the soma juice, seeking the heavenly planets, worship Me indirectly. They take birth on the planet of Indra, where they enjoy godly delights.” But the next verse of Bhagavad-gītā says that when one uses up the results of these pious activities, one has to forfeit his status as a demigod, along with the pleasure of the heavenly kingdom, and return to earth as a nara, or ordinary human being (kṣīṇe puṇye martya-lokaṁ viśanti). In fact the laws of nature are so subtle that one may not even return to earth as a human, but may take birth as an insect or tree, depending on the particular configuration of his karma.”
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Eleventh Canto, Chapter 02 – Text 49.
