We have already seen that the essence of life in the higher Lokas is unselfishness. It is for this reason that the Gitâ speaks of unselfish action in the first instance as an essential requisite of spiritual life. But it is not unselfish action alone which enables us to get rid of our personal desires and to assimilate ourselves with that one life which pervades all. Devotional love is another equally essential requisite. It is impossible for us to realise the different experiences in the four higher Lokas. The famous Brahma Sûkta has the following line: — "The three feet of Ísvara, bearing eternal happiness in the higher Lokas." The eighteenth Śloka in Chapter VI. of the Second Skandha is an exposition of this line. Śridhara has the following commentary on that line: "Happiness in Trilokî is fleeting and temporary. Though Mahar Loka is on the path of liberation, the dwellers of that Loka have to leave it at the end of every Kalpa. The happiness there is therefore not ever-lasting. In Jana Loka, the happiness is ever-lasting, as long as the dwellers do not leave the place. But they have to witness the miseries of the dwellers of Mahar Loka, when they come to Jana Loka, at the end of the Kalpa. In Tapas, there is absolute want of evil. In Satya, there is freedom from fear or liberation." We have left the Devas (not the elementals that pass through the life kingdoms of this earth) out of consideration. Their evolution is worked out in all the seven Lokas. Their names and characteristics in each Loka are given by Vyâsa in his commentaries on Patanjali’s Sutras. Those who are ordinarily known as Devas are the dwellers of Svar Loka. The Deva Yonis or lower Devas are dwellers of Bhuvar Loka and Bhûr Loka. Men have nothing to do with the Devas of the higher Lokas. The Devas of Trilokî are indifferent, friendly or inimical to men. Left alone, they do not interfere with men. But when men try to gain superiority over them, by the acquisition of Brahma Vidyâ, they try to throw obstacles in their way. The Brihad Âranyak Upanishad says: — "Even the gods verily are not able to prevent him from the possession of the state of all." I.-4-10 Again, "As verily many beasts maintain a man, so every man maintains the gods. It is not pleasant, even if one beast is taken away, how then, if many? Therefore it is not pleasant to them, that men should know this _i.e._ the truth of the nature of Brahmâ." Commenting on this, Śankarâchâryya quotes a Śloka from Anugrta: "The world of the gods is surrounded by performers of works. But the gods do not wish that mortals should abide above." Śankarâchâryya goes on to say: — "Therefore the gods try to exclude, like cattle from tigers, men from the knowledge of Brahmâ, as it is their desire, that they should not be elevated above the sphere of their use. Whom they wish to liberate, to him they impart belief &c., and unbelief to him whom they wish not to liberate."