What each character is grounded in.

Marcus's private journals. The text covers Stoic philosophy in practice: duty, virtue, acceptance, self-discipline, the nature of time and death, the inner citadel, leadership in service of the common good, and his own self-criticism in trying to live up to his ideals.

The included scholarly introduction covers his life and reign. Public domain edition, Project Gutenberg.

Cassius Dio's account of Marcus's reign as emperor. Covers the Marcomannic Wars on the Danube, the Antonine Plague, his co-emperor Lucius Verus, the rebellion of Cassius and Marcus's merciful response, military campaigns and troop relations, the succession decision that produced Commodus, and his death in 180 AD.

Marie's biography of Pierre, with autobiographical notes covering her own childhood and education in Poland. Tells the radium story through the partnership: the shed laboratory, years of manual labor, the philosophy of pure research, the French academic establishment and its barriers to women. It also holds their refusal to profit from radium, in her words: "We took out no patent."

The doctoral thesis on radioactivity. Systematic study of radium, polonium, uranium, and thorium. Measurement methodology with the electrometer, quantitative analysis of radioactive elements, chemical separation and purification methods, emanation and half-life, and the theoretical implications for atomic structure.

Marie's 1921 public lecture at Vassar. A rare direct account: how radium was isolated, the shed laboratory, the years of perseverance, the moment of discovery, Pierre's partnership, and her view that science must be done "for itself, for the beauty of science," with the chance that a discovery becomes "a benefit for humanity."

Marie's daughter Eve Curie's biography of her mother. Covers Marie's childhood in Russian-occupied Poland, near-starvation as a student in Paris, the meeting and courtship with Pierre, the Nobel Prize years, Pierre's death by horse cart, the World War I mobile X-ray units she drove to the front, the Langevin scandal, the American tours, and her final years of declining health from radiation exposure.

The note that names polonium. The search in pitchblende for something more active than uranium, the separation by sulphides and by sublimation, a substance 400 times as active as uranium, and the name, chosen "after the native country of one of us."

Two texts. The December 1898 note that names radium, written with Bémont: a barium extract 900 times as active as uranium, Demarçay's new line in its spectrum, and a faint glow that seemed to challenge Carnot's principle. Then Marie's own survey of February 1899 for a general scientific reader: the rays of uranium and thorium, the minerals that give them off, and polonium.

Her first lecture at the Sorbonne, opening the general physics course she took over after Pierre's death. Electrons and the atomic nature of electricity, ions in liquids and gases, Faraday and Maxwell, and radioactivity as a change inside the atom, an idea she notes she and Pierre put forward early and Rutherford and Soddy developed.

Science's short report of the White House ceremony, where President Harding presented a gram of radium valued at $120,000, the gift of the women of America, with her reply in full: her thanks to him and to them "in the name of France" and "in the name of humanity."

Harding's speech presenting the gram of radium. It records how the President framed her visit and her work; it says nothing of how she looked or spoke. Her reply is the card above.

Her reply on receiving $50,000 to buy a gram of radium for the Radium Institute in Warsaw. "My work is very much my life," she says, and calls the value of pure science "the creed of my life." She remembers Hoover's relief work in Poland and ties her Paris laboratory to the Warsaw institute.

Four short wire reports. Her arrival in New York on 11 May 1921: the "simple black tailored suit," the "almost ashen whiteness of skin," radium as a cure "if it is applied properly," and the Polish societies at the pier. Her second arrival in October 1929 and her doctors' worry. And the Hoover ceremony, where she thanked him "in a voice scarcely audible."

The first and most concentrated autobiography. Written in 1845, seven years after his escape. Slavery firsthand: daily life, brutality, learning to read in secret, the psychological corruption slavery inflicts on slaveholders, and the escape from Baltimore (kept deliberately vague to protect the network).

The second autobiography, written ten years later with more distance and analysis. Expanded detail on his grandmother's cabin, Sophia Auld teaching him letters and then being forbidden, the fight with Covey as a psychological turning point, escape planning and betrayal, and a more sophisticated analysis of slavery as a system rather than only a set of cruelties.

The third autobiography, in its 1881 edition. Covers the abolitionist movement, his friendship and tensions with William Lloyd Garrison, his relationship with John Brown and Harpers Ferry, meeting Lincoln, recruiting the 54th Massachusetts, Reconstruction's hopes and betrayals, and his appointments as U.S. Marshal and Recorder of Deeds for the District of Columbia. The chapters he added in 1892, his years as Minister to Haiti among them, are not in his library, and neither is his 1884 marriage to Helen Pitts.

The 1905 paper that revolutionized physics. The original derivation of special relativity: Lorentz transformations, the relativity principle, the absolute versus relative nature of simultaneity, time dilation, length contraction, and the transformation of electromagnetic fields between moving reference frames.

The short 1905 paper that introduced mass-energy equivalence. The original derivation of E=mc² in Einstein's own words, energy content of bodies, and the implications for the relationship between matter and radiation.

One of the 1905 annus mirabilis papers, the first of the five in Cowper's collection. Theory of Brownian motion, the molecular-kinetic explanation, statistical mechanics, and a test of the atomic hypothesis through measurable particle motion.

Einstein's own popular exposition of relativity, written for the educated lay reader. Special relativity, general relativity, curved spacetime, gravity as geometry, and the thought experiments he used to teach the theory. Short sentences, concrete analogies, building from simple premises.

Einstein's 1921 Princeton lectures, four lectures unifying special and general relativity at mid-level rigor. Spacetime and non-Euclidean geometry, gravity as curved spacetime, tensor calculus, cosmology, the principle of equivalence, and the relationship between physical reality and mathematical description.

Two complete public addresses. "Ether and the Theory of Relativity" (1920 Leiden) covers the history of the ether concept and the philosophical shift from mechanical to field-based physics. "Geometry and Experience" (1921 Berlin) covers the relationship between mathematics and physical reality.

The letter Einstein co-signed warning Roosevelt that nuclear chain reactions in uranium could produce a weapon, and that Germany was likely pursuing it. The document that catalyzed the Manhattan Project.

A short biographical entry written by F.A. Lindemann in 1922. Useful for dating milestones (the Bern patent office to 1909, the chairs at Zurich and Prague, the Berlin post of 1914, the Royal Society in 1921) and for understanding how Einstein was viewed in real time by the scientific establishment.

The Swiss IPI's institutional record of Einstein's patent examiner years. Friedrich Haller as director, Einstein's own description of patent review as a "cobbler's trade," Room 86, and the institutional context of his annus mirabilis years.

Theory of light, shadow, and color in painting. Optical phenomena, the perspective of color, atmospheric effects, the science of seeing, chiaroscuro technique grounded in physics.

Practical painting instruction. Composition, technique, the artist's materials. How to depict figures, emotions, and movement. Studio practice and workshop methods. Critiques of other painters and common errors.

Philosophy of knowledge: experience versus authority, science versus dogma. Observations on human nature and society. Physiology, astronomy, physical geography (water, rivers, mountains, the fossil shells), and a few notes on flying machines. Personal letters and records, the 1482 letter to Ludovico Sforza and his will among them. Humor, fables, jests and prophecies, and the passages where Leonardo is frustrated.

Notes on sculpture, the Sforza horse and its casting among them. Architectural designs (town plans for Milan, churches, palaces) and the theory of building: cracks, arches, foundations, beams. Then anatomy and zoology, his dissection notes among them.

The proportions of the human figure, the Vitruvian proportions among them, and how the body moves, as a painter needs to draw it.

Botanical observation (tree growth, leaf arrangement, plant movement) and landscape painting (mountains, water, weather, atmosphere). The science of representing nature accurately.

Chronological biography from birth in Vinci through death in France. Verrocchio apprenticeship, the first Milan period and The Last Supper, the Mona Lisa, the Michelangelo rivalry, the Roman period, the final years in France under Francis I. Personality notes on restlessness, perfectionism, and his pattern of abandoning projects.

Vasari's Life of Leonardo from the 1568 edition, in Herbert Horne's English, with Horne's commentary. It holds most of the famous Leonardo stories, and Horne answers Vasari's errors as they stood in 1903. The commentary also gives two early accounts in English, the Anonimo Gaddiano and Sabba da Castiglione: his looks and the rose-colored tunic, the Dante quarrel with Michelangelo, and the Gascon crossbowmen who used the clay horse as a target.

The Sforza court during Leonardo's first Milan period: Ludovico, Beatrice, Cecilia Gallerani, the Paradiso of 1490, the 1491 wedding masques and tournament, the clay horse and the Last Supper as the court saw them, and the fall of Milan in 1499.

Two chapters on Isabella d'Este and Leonardo: his visit to Mantua at the end of 1499 and his portrait drawing of her, then her letters to him from 1500 to 1506, with Fra Pietro da Novellara's letters of April 1501, an eyewitness record of his working days: "He is working hard at geometry, and is quite tired of painting."

One chapter of Müntz's study: Leonardo's scientific method, his mathematics, physics and the camera obscura, natural history, and his work as engineer and mechanician, the material Richter's edition of the Notebooks set aside.

The most vivid ancient account of Cleopatra and Antony. The barge on the Cydnus, her multilingualism, the Donations of Alexandria, the Battle of Actium and its aftermath, Antony's decline and death, Cleopatra's own death and final defiance. The source Shakespeare drew on.

The Caesar and Octavian sections. Caesar and Cleopatra in Egypt, her presence in Rome during Caesar's final years, Octavian's propaganda campaign against her as a "foreign queen" threatening Rome, the Battle of Actium from the Roman perspective, and the political aftermath that transformed Rome into Empire.

The most thorough biography of Cleopatra in the public domain. Written by Arthur Weigall, former Inspector-General of Egyptian Antiquities. The Ptolemaic dynasty and palace intrigue, her education in Alexandria, the Library and Museum, the civil war with her brother Ptolemy XIII, her economic and administrative policy, and the broader geopolitical context. Tells the Egyptian story that the Roman historians don't.