La Rochefoucauld writes, “Le soleil ni la mort ne se peuvent regarder fixément”: “Neither the sun nor death can be stared at (looked at fixedly)” (Maxim 19, edition of 1678.)  In each case seeing would undo sight.  But impossibility is apt to be disregarded.  We may think of the peril of raising one’s eyes to the Sun King; or of a philosopher who, following Socrates, practices dying and being dead (Phaedo 64a), until he becomes unable to see life as others do.

The blindness or darkness that ensues in such cases has been represented as the condition of a castaway, one shipwrecked.  Thus the men of Odysseus appropriate the cattle of Helios Hyperion, the Sun that is Over, and having so raised their eyes to the god, they slay his beasts ὑπέρβιον, hyperbion, over-boldly (Odyssey 1.8, 12.379).  Demanding atonement, Helios threatens to go down to Hades and shine among the dead; to satisfy him Zeus blasts the men out of Odysseus’s ship with a thunderbolt and destroys it.  Their leader, who had condemned the sacrilege, is saved alone, to be carried all but helpless to Calypso’s island.  —What the god Odysseus offended (by proxy) would have done is to blind the living world and reveal the thinness of the one below.  By this the hero’s affinity with him is evident, for Odysseus too is a blinder—not only of the Cyclops, but of many men by his disguises, including the Trojan horse, and the cloak of his speech—and himself visits the dead, illuminating them but experiencing their emptiness.

Again, Milton’s Satan, “fraught / With envy against the Son of God,” (Paradise Lost 5.661) is cast “Thunder-struck” (6.858) with his followers into “a fiery Gulf” in “darkness visible,” (1.52, 63) from which he makes his way to land.  He resembles a sun darkened:

His form had not yet lost

All her Original brightness, nor appear’d
Less than Arch-Angel ruin’d, and th’ excess
Of Glory obscur’d: As when the Sun new ris’n
Looks through the Horizontal misty Air
Shorn of his Beams, or from behind the Moon
In dim Eclipse disastrous twilight sheds
On half the Nations, and with fear of change
Perplexes Monarchs.  Dark’n’d so, yet shone
Above them all th’ Arch-Angel: but his face
Deep scars of Thunder had intrencht…

At the gate of his new world Satan encounters Sin and “her black attendant Death” (7.547),

The other shape,

If shape it might be call’d that shape had none
Distinguishable in member, joint, or limb,
Or substance might be call’d that shadow seem’d,
For each seem’d either—black it stood as Night…

Death is unseeable, or unknowable, because it has no form; in Greek, no eidos.  —This is the very idea that frightens people about Hades, Socrates thinks: the name of the place (that is, of the god whose place it is), Ἅιδης, Haidēs, resembles ἀειδής, aeidēs, which is ἀ-εἶδος, a-eidos, ‘without form,’ ‘invisible,’ ‘unknowable’ (Cratylus 403a).  In truth, their anxiety is unwarranted: it is the world that is ever-changing, while the ideal realm of the invisible is the proper place of the soul that is like it (Phaedo 79a–81d).

The blind poets’ notions of Heaven’s light gone down to shine in the underworld, and of the darkness below risen up to infect the world above—both suggest the curious image of a black sun.  Where was it first formulated in this phrase?  The first occurrence I am aware of is in Heine’s Der Schiffbrüchige, The Shipwrecked One, whose eponymous figure describes by it the eye of his lost beloved:

…Und aus dem süßen, blassen Antlitz,
Groß und gewaltig, strahlt ein Auge,
Wie eine schwarze Sonne.

O, du schwarze Sonne, wie oft,
Entzückend oft, trank ich aus dir
die wilden Begeistrungsflammen…

…And out of her sweet, pale face,
large and powerful, beams an eye,
like a black sun.

O thou black sun, how often,
enchantingly often, I drank from thee
wild flames of inspiration…

Now he lies on a barren shore.  A quarter-century later Nerval uses the expression in his famous El Desdichado, which begins:

Je suis le ténébreux, — le veuf, — l’inconsolé,
Le prince d’Aquitaine à la tour abolie :
Ma seule étoile est morte, — et mon luth constellé
Porte le Soleil noir de la Mélancolie.

I am the dark one,—the widower,—the unconsoled,
the prince of Aquitaine with the ruined tower:
my only star is dead,—and my star-spangled lute
bears the black Sun of Melancholy.

Elsewhere (as the Pléiade edition points out) he alludes to “the black sun of melancholy, which sheds dark rays upon the face of the dreaming angel of Albert [sic] Dürer”; thus the allusion is to the well-known engraving “Melencolia I.”  Without going further into this poem, I note that in its own way it seems to continue the theme of the castaway.  Following Walter Scott’s error in Ivanhoe, Nerval presumably thinks the Spanish title means “The Disinherited One,” separated from his patrimony; and in his lostness the speaker resembles Keats’s knight, “alone and palely loitering.”  He says, “J’ai rêvé dans la grotte où nage la syrène…,” “I have dreamed in the grotto where the siren swims…”; but unlike Odysseus, he has acquired the knowledge she imparts.

After all I suppose the theme of shipwreck is nothing more than a particular case of the favorite condition of the poets, that of exile.