The deity said, you have grieved for those who deserve no grief . . . Learned men grieve not for the living nor the dead. Never did I not exist, nor you, nor these rulers of men; nor will any one of us ever hereafter cease to be. As in this body, infancy and youth and old age come to the embodied self, so does the acquisition of another body; a sensible man is not deceived about that. The contacts of the senses, O son of Kunti! which produce cold and heat, pleasure and pain, are not permanent, they are ever coming and going. Bear them, O descendant of Bharata! For, O chief of men! that sensible man whom they (pain and pleasure being alike to him) afflict not, he merits immortality. There is no existence for that which is unreal; there is no non-existence for that which is real. And the correct conclusion about both is perceived by those who perceive the truth. Know that to be indestructible which pervades all this . . . He who thinks it  to be the killer and he who thinks it to be killed, both know nothing. It kills not, is not killed. It is not born, nor does it ever die, nor, having existed, does it exist no more. Unborn, everlasting, unchangeable, and primeval, it is not killed when the body is killed. O son of Pritha! how can that man who knows it thus to be indestructible, everlasting, unborn, and inexhaustible, how and whom can he kill, whom can he cause to be killed? As a man, casting off old clothes, puts on others and new ones, so the embodied self, casting off old bodies, goes to others and new ones . . . It is everlasting, all-pervading, stable, firm, and eternal. It is said to be unperceived, to be unthinkable, to be unchangeable. Therefore, knowing it to be such, you ought not to grieve. But even if you think that it is constantly born and constantly dies, still, O you of mighty arms! you ought not to grieve thus. For to one that is born, death is certain; and to one that dies, birth is certain . . .
– Bhagavad Gita