Those gods who were connected with the sky may have been held to dwell there or on the mountain supporting it. Others, like the Celtic Dispater, dwelt underground. Some were connected with mounds and hills, or were supposed to have taken up their abode in them. Others, again, dwelt in a distant region, the Celtic Elysium, which, once the Celts reached the sea, became a far-off island. Those divinities worshipped in groves were believed to dwell there and to manifest themselves at midday or midnight, while such objects of nature as rivers, wells, and trees were held to be the abode of gods or spirits. Thus it is doubtful whether the Celts ever thought of their gods as dwelling in one Olympus. The Tuatha Dé Danann are said to have come from heaven, but this may be the mere assertion of some scribe who knew not what to make of this group of beings. In Celtic belief men were not so much created by gods as descended from them. "All the Gauls assert that they are descended from Dispater, and this, they say, has been handed down to them by the Druids."[770] Dispater was a Celtic underworld god of fertility, and the statement probably presupposes a myth, like that found among many primitive peoples, telling how men once lived underground and thence came to the surface of the earth. But it also points to their descent from the god of the underworld. Thither the dead returned to him who was ancestor of the living as well as lord of the dead.[771] On the other hand, if the earth had originally been thought of as a female, she as Earth-mother would be ancestress of men. But her place in the myth would easily be taken by the Earth or Under-earth god, perhaps regarded as her son or her consort. In other cases, clans, families, or individuals often traced their descent to gods or divine animals or plants. Classical writers occasionally speak of the origin of branches of the Celtic race from eponymous founders, perhaps from their knowledge of existing Celtic myths.[772] Ammianus Marcellinus also reports a Druidic tradition to the effect that some Gauls were indigenous, some had come from distant islands, and others from beyond the Rhine.[773] But this is not so much a myth of origins, as an explanation of the presence of different peoples in Gaul--the aborigines, the Celtæ, and the Belgic Gauls. M. D'Arbois assumes that "distant islands" means the Celtic Elysium, which he regards as the land of the dead,[774] but the phrase is probably no more than a distorted reminiscence of the far-off lands whence early groups of Celts had reached Gaul.