"He was a savage Antinous"
Hadrian's (Roman Emperor 117-138 A.D.) young Bithynian companion, who drowned in the Nile in 130 A.D., and who was afterwards deified by the emperor.
(Note: This is not a ref to The Odyssey, in which Antinous is one of the prominent suitors of Odysseus' wife Penelope.)

"On Mount Aventine, he would have been Gracchus"
Apparently a ref to Gaius Sempronius Gracchus; he and his followers occupied Aventine Hill and fortified it, but were killed by army; this was the end of Repblican Rome. Younger brother to Tiberius. Was tribune in 123 and 122 B.C.
(Note: this is not a ref to "Gracchus" Babeuf, aka Francois-Noel Babeuf, who led 1796 "Conspiracy of Equals," a communist tradition of the Revolution. Plotted to overthrow the Directory and replace it with a materialist utopia in which all property would be held collectively under a regime of literal equality.)

"in the Convention, he would have been Saint-Just"
The Convention established its revolutionary government in the Law of 14 Frimaire Year II (Dec. 4, 1793). This law set up the Committee of Public Safety, which was at the head of those who organized the French Revolution: it controlled military policy and patronage, local administrators (renamed national agents), tribunals, and revolutionary committees. Saint-Just was a member of the Committee, close to Robespierre, and fervently against any who opposed the Revolution. On July 27, 1794, the Convention ordered the arrest of Robespierre and Saint-Just; on the 28th, they were guillotined without trial.

"the bare throat of Evadne"
Evadne was a Greek tragic character, the wife of Capaneus. Included in the works of Euripides and Ovid, Evadne committed suicide by flinging herself upon the funereal pyre of her husband. Capaneus was one of the Seven Against Thebes, who died attempting to overthrow the rule of Eteocles. (Which fits in with the whole Saint-Just/Aristogeiton coups theme.) [thanks to Lawrence Kwong]

Aristogeiton/Harmodius
Two men who plotted to overthrow the tyrants ruling Athens in 514 BC, killing the tyrant Hipparchus. They were only partly successful in their plans, but later received full recognition as heroes.

"mighty cherub of Ezekiel"
Biblical: Highest order of angels, described in Ezekiel 10.

"gallant Cherubino of Beaumarchais"
Cherubino is the flirtatious young man in Beaumarchais' comedic play "Le Mariage de Figaro" (later adapted to the opera Le nozze di Figaro by Mozart and Lorenzo da Ponte).

Robespierre
Maximilien de Robespierre (1758-1794), supporter of the decocratic republic and equality, leader of the Jacobins and of The Terror during the French Revolution. Nicknamed "l'Incorruptible." Guillotined July 28, 1794 by the Convention.

Condorcet
Marie Jean Antoine Nicolas de Caritat Condorcet (1743-1794), Marquis de Condorcet. Mathematician (probability and philosophy of mathematics), appointed Secretary of the Académie des Sciences in 1777; by 1792 had become one of the leaders of the Republican cause. Opposed the constitution drawn up by the Jacobins; died in prison 1794.

"learned the polarization of light from Arago"
Dominique Arago (1786-1853), French physicist.

"Geoffrey Sainte-Hilaire explained the double function of the external carotid artery"

"compared Saint-Simon with Fourier"
Two utopian socialists.

"studied Puysegur and Deleuze"
Marquis de Puysegur (Armand Marie Jacques de Chastenet) and Joseph Philippe Francois Deleuze, both of whom studied hypnotism and animal magnetism.

"there exists between Washington, who represents the one, and Danton, who incarnates the other"

"blamed the Revolution for having caused the fall of a royal head, that of Andre Chenier"
Early French Romantic poet, executed during the Terror. His poems were first published in 1819.

"four poets: Dante, Juvenal, AEschylus, and Isaiah"
Dante Alighieri, author of The Divine Comedy; Juvenal, Roman satirist, author of Satires; Aeschylus, Greek playwright; Isaiah, prophet during the expansion of the Assyrian empire and writer of one of the books of the Old Testament.

Corneille/Racine/Agrippa d'Aubigne
The poets Pierre Corneille, Jean Racine, and Theodore Agrippa d'Aubigne.

"infamous date of 1772"
First partition of Poland by Russia, Prussia, and Austria.

"the epoch of la Minerve"

beaute du diable
Literally, "beauty of the devil." (Fr.)

quasi cursores
Part of the Latin motto "Quasi Cursores Vitai Lampada Tradunt," which means "Like runners they carry the torch of life." [thanks to Lawrence Kwong]

"the burial of young Lallemand"

Loizerolles
Jean-Simon Aved de Loizerolles (?)

Vive Henri IV
Composed by Franz Liszt (1811-1886).

"They are Pollux, Patrocles, Nisus, Eudamidas, Ephestion, Pechmeja"
Pollux, brother of Castor, son of Leda and Jupiter, and one of the twins of the Gemini constellation; Patrocles (or Patroklos), personal attendant of Achilles and killed in the Trojan wars; Nisus, king of Megara, father of Scylla, at war with King Minos of Crete; Eudamidas, brother of Phoebidas, both generals (?) in the Spartan army; Jean de Pechmeja (?)

Orestes and Pylades
Orestes, son of Agamemnon and Clytemnestra, who avenged his father's death at his mother's hands; Pylades, son of Strophius (King of Phocis). The two became supremely close friends after Orestes was for his own safety sent away to live at the court of Strophius. [Following contributed by Stephanie Tsulin] The only reason why Pylades is known is beacuse he was this supremely close friend of Orestes. Pylades himself never did anything worth remembering; he is only remembered as Orestes' friend. I think adding this bit of info is important as that is the only reason why Hugo makes this reference of Enjolras and Grantaire.

Erudimini qui judicatis terram
(Lat.) Receive instruction, you that judge the earth.