What 'internal' or 'divine' sign is Socrates referring to in The Republic when talking about the scarcity of true philosophers?

Question

What does Plato in Book VI of The Republic (496c) refer to when writing the following words of Socrates:

My own case, the divine sign, is hardly worth mentioning—for I suppose it has happened to few or none before me.

Or within its context in Benjamin Jowett's translation:

Then, Adeimantus, I said, the worthy disciples of philosophy will be but a small remnant: perchance some noble and well-educated person, detained by exile in her service, who in the absence of corrupting influences remains devoted to her; or some lofty soul born in a mean city, the politics of which he contemns and neglects; and there may be a gifted few who leave the arts, which they justly despise, and come to her; --or peradventure there are some who are restrained by our friend Theages' bridle; for everything in the life of Theages conspired to divert him from philosophy; but ill-health kept him away from politics. My own case of the internal sign is hardly worth mentioning, for rarely, if ever, has such a monitor been given to any other man. Those who belong to this small class have tasted how sweet and blessed a possession philosophy is, and have also seen enough of the madness of the multitude; and they know that no politician is honest, nor is there any champion of justice at whose side they may fight and be saved. Such an one may be compared to a man who has fallen among wild beasts --he will not join in the wickedness of his fellows, but neither is he able singly to resist all their fierce natures, and therefore seeing that he would be of no use to the State or to his friends, and reflecting that he would have to throw away his life without doing any good either to himself or others, he holds his peace, and goes his own way. He is like one who, in the storm of dust and sleet which the driving wind hurries along, retires under the shelter of a wall; and seeing the rest of mankind full of wickedness, he is content, if only he can live his own life and be pure from evil or unrighteousness, and depart in peace and good-will, with bright hopes.

Answer 1

Per: https://en.wiktionary.org/wiki/δαιμόνιον the 'internal' or 'divine' sign is
"the name by which Socrates calls his genius, or the spirit that dwelt within him" (noun 2.1)

Alternative translation of Republic Book VI, 496c, by G.M.A. Grube, rev. C.D.C. Reeve:

Finally, my own case is hardly worth mentioning — my daemonic sign — because it has happened to no one before me, or to only a very few.

In "The Complete Works of Plato" edited by John M. Cooper, see also Cratylus 397c - 398c (translation by C.D.C. Reeve) where the wisdom of the δαιμόνιον is mentioned (in the context of examining names):

SOCRATES: It is principally because daemons are wise and knowing (daē-mones), I think, that Hesiod says they are named ‘daemons’ (‘daimones’). In our older Attic dialect, we actually find the word ‘daēmones’. So, Hesiod and many other poets speak well when they say that when a good man dies, he has a great destiny and a great honor and becomes a ‘daemon’, which is a name given to him because it accords with wisdom. And I myself assert, indeed, that every good man, whether alive or dead, is daemonic, and is correctly called a ‘daemon’.

(boldface my own) ...and the following footnote is given:

Daemons are gods or children of the gods (Apology 27d–e) or messengers from the gods (Symposium 202e).

In Republic Plato's character Socrates uses the internal, daemonic or "divine sign" in this sense of being a message from one of these "messengers" of divinity. His meaning is that of inspiration, epiphany or a call to reflection or reasoning (as contrasted to a call to action) such that the inspiration has the quality of being different or "other" than those experiencing the inspiration and "seeing" the demonic/divine sign.

Apology 31d, translation by G.M.A. Grube:

I have a divine or spiritual sign which Meletus has ridiculed in his deposition. This began when I was a child. It is a voice, and whenever it speaks it turns me away from something I am about to do, but it never encourages me to do anything.

Note that this sense of "daemonic" has nothing at all to do with christian notions of the devil or the moralizing of the "demon" in any sense of "good or evil." It is more akin to the sense of the fictional character "Lucifer" whose name means the "bringer of light" (as if "light" were "knowledge" or "wisdom"). The Greek use of the term is more akin to a "lesser" deity or "an inferior divine being, demon" (noun 2) as compared to "‘theoi’ (‘gods’)", which is further discussed in Cratylus 397c - 398c. In this sense, Plato is using Socrates to describe the character of philosophers similar to Socrates dialogue in Plato's Theaetetus 174-175 such that the "divine/daemonic sign" is that which compels the philosopher to philosophical contemplation.

For a thorough dissertation upon "Socrates's daimonic thing", see:

"Daimonion of Socrates: A Search for Definition and an Epistemological Assessment" by Alton R. Pope,

"The Daimonion and the Philosophical Mission - Should the Divine Sign Remain Unique to Socrates?" by Pierre Destrée,

and

"The Philosophy: From Under the Sign of a Daimonion" by Waldemar Pycka, translated by Marcin Mizak.