The third part of the Kena Upanishad, in setting forth what is called “the parable of the gods” systematically looks at the powers of creation of matter, life and mind, poses them a riddle and a test, and points out to us that there is something beyond, unknown, which is the real creative force from which each of them is simply a derivative and subsidiary power. The gods named, Agni, Vayu and Indra, represent matter, life and mind respectively. Agni, the “knower of all things born” is the first one put to the test, consistent with the evolutionary development from matter, to life, and from thence to mind, that we can identify in our world.
Third part, verse 3-6: “They said to Agni, ‘O thou that knowest all things born, learn of this thing, what may be this mighty Daemon, ‘ and he said “So be it.’ He rushed towards the Eternal and It said to him, ‘Who art thou?’ ‘I am Agni,’ he said, ‘I am he that knows all things born.’ ‘Since such thou art, what is the force in thee?’ ‘Even all this I could burn, all that is upon the earth.’ The Eternal set before him a blade of grass; ‘This burn,’ and he made towards it with all his speed, but he could not burn it. There he ceased, and turned back; ‘I could not know of It, what might be this mighty Daemon.’ ”
Sri Aurobindo observes: “Here the three gods Indra, Vayu, Agni represent the cosmic Divine on each of its three planes, Indra on the mental, Vayu on the vital, Agni on the material. In that order, therefore, beginning from the material they approach the Brahman. Agni is the heat and flame of the conscious force in Matter which has built up the universe; it is he who has made life and mind possible and developed them in the material universe where he is the greatest deity. Especially he is the primary impeller of speech of which Vayu is the medium and Indra the lord. This heat of conscious force in Matter is Agni Jatavedas, the knower of all births: of all things born, of every cosmic phenomenon he knows the law, the process, the limit, the relation. If then it is some mighty Birth of the cosmos that stands before them, some new indeterminate developed int he cosmic struggle and process, who shall know him, determine his limits, strength, potentialities if not Agni Jatavedas?”
The first to explore the issue is Agni: “His name is Agni Jatavedas, the Power that is at the basis of all birth and process in the material universe and embraces and knows their workings and the force in him is that all that is thus born, he as the flame of Time and Death can devour. All things are his food which he assimilates and turns into material of new birth and formation. But this all-devourer cannot devour with all his force a fragile blade of grass so long as it has behind it the power of the Eternal. Agni is compelled to return, not having discovered. One thing only is settled that this Daemon is no Birth of the material cosmos, no transient thing that is subject to the flame and breath of Time; it is too great for Agni.”
Sri Aurobindo, The Upanishads, Kena Upanishad and analysis, pp. 104-106, 171-176