They are mostly addressed in the dual, as two beings forming but one concept. We meet, however, with verses which are addressed to the Earth by herself, and which speak of her as "kind, without thorns, and pleasant to dwell on,"[176] while there are clear traces in some of the hymns that at one time Dyaus, the sky, was the supreme deity.[177] When invoked together they are called D y â v â - p_ r i_ t h i v y a u, from d y u, the sky, and p _r i_ t h i v î, the broad earth. If we examine their epithets, we find that many of them reflect simply the physical aspects of Heaven and Earth. Thus they are called u r u, wide; u r u v y a _k_ a s, widely expanded, d û r e - a n t e, with limits far apart, g a b h î r a, deep; g h _r i_ t a v a t, giving fat; m a d h u d u g h a, yielding honey or dew; p a y a s v a t, full of milk; b h û r i - r e t a s, rich in seed. Another class of epithets represents them already as endowed with certain human and superhuman qualities, such as a s a _s k_ a t, never tiring, a _g_ a r a, not decaying, which brings us very near to immortal; a d r u h, not injuring, or not deceiving, p r a _k_ e t a s, provident, and then pitâ-mâta, father and mother, devaputra, having the gods for their sons, _r i_ t a - v_ r i_ d h and _r i_ t a v a t, protectors of the _Ri_ta, of what is right, guardians of eternal laws. Here you see what is so interesting in the Veda, the gradual advance from the material to the spiritual, from the sensuous to the supersensuous, from the human to the superhuman and the divine. Heaven and Earth were seen, and, according to our notions, they might simply be classed as visible and finite beings. But the ancient poets were more honest to themselves. They could see Heaven and Earth, but they never saw them in their entirety. They felt that there was something beyond the purely finite aspect of these beings, and therefore they thought of them, not as they would think of a stone, or a tree, or a dog, but as something not-finite, not altogether visible or knowable, yet as something important to themselves, powerful, strong to bless, but also strong to hurt. Whatever was between Heaven and Earth seemed to be theirs, their property, their realm, their dominion. They held and embraced all; they seemed to have produced all. The Devas or bright beings, the sun, the dawn, the fire, the wind, the rain, were all theirs, and were called therefore the offspring of Heaven and Earth. Thus Heaven and Earth became the Universal Father and Mother.