Moreover, we admit that hymns of true feeling may be composed late as well as early, while as to beauty of style the chances are that the best literary production will be found among the latest rather than among the earliest hymns.
It would, indeed, be admissible, if one had any certainty in regard to the age of the different parts of the Rig Veda, simply to divide the hymns into early, middle, and late, as they are sometimes divided in philological works, but here one rests on the weakest of all supports for historical judgment, a linguistic and metrical basis, when one is ignorant alike of what may have been accomplished by imitation, and of the work of those later priests who remade the poems of their ancestors.
Best then, because least hazardous, appears to be the method which we have followed, namely, to take up group by group the most important deities arranged in the order of their relative importance, and by studying each to arrive at a fair understanding of the pantheon as a whole.

The Hindus themselves divided their gods into highest, middle, and lowest, or those of the upper sky, the atmosphere, and the earth.
This division, from the point of view of one who would enter into the spirit of the seers and at the same time keep in mind the changes to which that spirit gradually was subjected, is an excellent one.

For, as will be seen, although the earlier order of regard may have been from below upwards, this order does not apply to the literary monuments.

These show on the contrary a worship which steadily tends from above earthwards; and the three periods into which may be divided all Vedic theology are first that of the special worship of sky-gods, when less attention is paid to others; then that of the atmospheric and meteorological divinities; and finally that of terrestrial powers, each later group absorbing, so to speak, the earlier, and therewith preparing the developing Hindu intelligence for the reception of the universal god with whom closes the series.
Other factors than those of an inward development undoubtedly were at work in the formation of this growth.

Especially prominent is the amalgamation of the gods of the lower classes with those of the priest-hood.