Such a figure as Agni or Fire—if one can call him a figure—illustrates the fluid and intangible character of Vedic divinities. He is one of the greatest in the Pantheon, and in some ways his godhead is strongly marked. He blesses, protects, preserves, and inspires: he is a divine priest and messenger between gods and men: he "knows all generations." Yet we cannot give any definite account of him such as could be drawn up for a Greek deity. He is not a god of fire, like Vulcan, but the Fire itself regarded as divine. The descriptions of his appearance are not really anthropomorphic but metaphorical imagery depicting shining, streaming flames. The hymns tell us that he has a tawny beard and hair: a flaming head or three heads: three tongues or seven: four eyes or a thousand. One poem says that he faces in all directions: another that he is footless and headless. He is called the son of Heaven and Earth, of Tvashṭri and the Waters, of the Dawn, of Indra-Vishnu. One singer says that the gods generated him to be a light for the Aryans, another that he is the father of the gods. This multiple origin becomes more definite in the theory of Agni's three births: he is born on earth from the friction of fire sticks, in the clouds as lightning, and in the highest heavens as the Sun or celestial light. In virtue of this triple birth he assumes a triune character: his heads, tongues, bodies and dwellings are three, and this threefold nature has perhaps something to do with the triads of deities which become frequent later and finally develop into the Trimûrti or Brahmâ, Vishnu, and Siva. But there is nothing fixed or dogmatic in this idea of Agni's three births. In other texts he is said to have two, one in Heaven and one on Earth, and yet another turn of fancy ascribes to him births innumerable because he is kindled on many hearths. Some of the epithets applied to him become quasi-independent. For instance, Agni Vaiśvânara—All men's fire—and Agni Tanunapat, which seems to mean son of himself, or fire spontaneously generated, are in a later period treated almost as separate deities. Mâtariśvan is sometimes a name of Agni and sometimes a separate deity who brings Agni to mankind. In the same way the Rig Veda has not one but many solar deities. Mitra, Sûrya, Savitri, and perhaps Puśan, Bhaga, Vivasvat and Vishnu, are all loose personifications of certain functions or epithets of the sun. Deities are often thought of in classes. Thus we have the Maruts, Rudras and Vasus. We hear of Prajâpati in the singular, but also of the Prajâpatis or creative forces.