Laudator Temporis Acti

Thomas Keightley, The Mythology of Ancient Greece and Italy, 2nd ed. (London: Whittaker and Co., 1848), p. 233 (footnote omitted):

Like many other gods who were originally single, Pan was multiplied in course of time, and we meet with Pans in the plural.

Martin P. Nilsson, A History of Greek Religion, 2nd ed., tr. F.J. Fielden (New York: W.W. Norton & Company, Inc., 1964), pp. 111-113 (footnotes omitted):

Nature is full of these daimones: they are innumerable, for every spring, every tree, every natural object has or at least may have its daimon. Hence crowds of Nature daimones of various kinds arise. Within each homogeneous group the individual disappears in the aggregate; the daimon residing in a particular natural object has an extremely limited circle of worshippers; most have no cult but exist only in belief and imagination. In other domains also similar collective groups of spirits or gods appear, such as 'the gentle gods' (θεοὶ μειλίχιοι), 'the boisterous ones' (Μαιμακτῆρες), the goddesses of childbirth (the Ilithyiae), 'the holy goddesses', the Erinyes (σεμναὶ θεαί), and the 'Rulers' (Ἄνακες), the two sons of Zeus, the Dioskouroi.

And these spirits intervene in human life and fortune. Men turn to them for peace, happiness, and prosperity. Just as the harvest-rite could not embrace the entire crop standing upon the field, but a single sheaf was selected as representing the whole, so the cult cannot address itself to the collective group. The attention is fixed upon some particular one from among the host of similar spirits. If they are localized, the nearest is chosen; then a local god arises. If the localization is not made prominent, the singular is simply put for the plural: Pan is invoked instead of the Panes. It is significant that in so late a document as the record of the secular festival of the Emperor Augustus the Ilithyiae are everywhere named in the plural except in the prayer, where we read 'O thou, Ilithyia!' In a cave dedicated to the cult of the nymphs in Attica, in which various inscriptions were carved in the fifth century B.C., the nymphs are as a rule spoken of in the plural, but one dedication reads: 'Archedemos built to the nymph.'

The needs of man created the gods, and the cult is an expression of his need. A god is a daimon which has acquired importance and a fixed form through the cult. From among the crowd of similar beings the cult chooses one as its object, and this becomes a single god. But the belief in the numerous daimones lives on, and if both the single divinity and the group of daimones are present to the mind together, the latter acquire a leader. Thus we have Pan and the Panes, Silenus and the Sileni, but Silenus was reduced to a semi-comic figure when his retinue was absorbed in that of Dionysos. A great goddess who seems to have arisen in this way is Artemis. She is essentially nothing but the most prominent of the wood- and mountain-nymphs. With these she hunts and dances in mountains and forests and amid green meadows. Like them she rules the animals in wild Nature and fosters their young. Like them she extends her sway to men, helps the mother in her hour of need, and protects the rising generation, but she may also deal sudden death with her arrows. This tendency to exalt one among a number of similar beings to a position of supremacy was so ingrained that it has left an example dating from the time of transition to the Christian faith. The Lycian 'wild gods' are represented as twelve similar figures; to them a thirteenth was added as their ruler, and he was placed in the middle and was somewhat larger in size, but was in other respects just like the rest.