Lucretius, de rerum natura 5.1161-1182
Now what cause made the spirits of the gods spread through great races and filled cities with altars and took care that people tend to solemn sacrifices, the holy things which now flourish in great things and places, from where even now there comes an innate horror in mortals, which calls to life new shrines to the gods all over the world and compels people to celebrate in festal days – it is not hard to render an account of this in words. To be sure, even then mortal ages saw certain distinguished appearances with a waking mind, even more so when they saw them with marvelously increased bodies in their dreams.
They attributed sense to these because they seemed to move their limbs, to emit haughty voices with a noble face and ample strength. They gave eternal life, because their appearances were always fully fleshed out and their form remained unchanging, and yet they thought that those who were augmented by such strengths could not be conquered rashly by any power. They thought that these far excelled everyone else in good fortune, because the fear of death hardly ever vexed any of them, and because they saw them effect many miraculous things in dreams and take no effort in doing it.
Nunc quae causa deum per magnas numina gentis