The Road to Hell - A History of the Inquisition in the Middle Ages (Annotated)

- Annotated with suggested further readings and inline links to additional web content.

In 1843 Henry Charles Lea joined his father in business, and he retained his connection with the firm until 1880. In 1847, when he was twenty-two years old and had been working in the family publishing firm for four years, Lea suffered a nervous breakdown and abandoned his intellectual and scientific work for some time. During his period of convalescence Lea began reading French memoirs of the medieval period. They kindled his interest in medieval history and changed his career course from scientist to historian. Thereafter he focused on history, mainly on church history in the later Middle Ages, and on institutional, legal, and ecclesiastical history, as well as magic and witchcraft. He also did significant work on the history of the Italian city-states. His active writing career on historical subjects spanned more than fifty years, during which he published ten books and numerous articles. His literary reputation rests largely on the books he produced. These include:

Superstition and Force (Philadelphia, 1866, new ed. 1892) - Internet Archive
Historical Sketch of Sacerdotal Celibacy (Philadelphia, 1867) - Internet Archive
History of the Inquisition of the Middle Ages (New York, 1888) - Volume I
Chapters from the religious history of Spain connected with the Inquisition (Philadelphia, 1890)
History of auricular Confession and Indulgences in the Latin Church (3 vols., London, 1896) - Volume I, Volume II, Volume III
The Moriscos of Spain (Philadelphia, 1901)
History of the Inquisition of Spain (4 vols., New York and London, 1906€“1907) - Volume I, Volume II, Volume III, Volume IV.
He also edited a Formulary of the Papal Penitentiary in the 17th century (Philadelphia, 1892), and in 1908 was published his Inquisition in the Spanish Dependencies.

Lea discovered and acquired most of his materials from European sources, purchasing manuscripts and incunabula as well as other early printed books. The room holding his collection, built in 1881 as an extension to his house at 2000 Walnut Street, was conveyed to the University of Pennsylvania in 1926 by Lea's children.

Lea was treated by his friend Dr. S. Weir Mitchell, one of the country's most prominent doctors in the field of nervous disorders. Lea's highly disciplined habits of work enabled him to continue to write even as he suffered from headaches and problems with his eyes. He was very productive during the final twenty-five years of his life.

On 27 May 1850, Henry Charles Lea married Anna Caroline Jaudon (born 1824), his first cousin. During the American Civil War Lea was a member of the Union League of Philadelphia and was the head of its publication committee. He composed a number of the pamphlets published by the League. In 1863 he was appointed one of the Bounty Commissioners under the Enrolment Act and served until 1865, working closely with Provost Marshal General James B. Fry and members of his office responsible for accounting for the quotas of men enlisted from the city of Philadelphia. In this capacity he became involved with the efforts to recruit African American regiments to fight in the Union army.

Henry Charles Lea was outspoken on issues involving public projects and public health in Philadelphia. He strongly opposed the building of City Hall at the Penn Square location at the intersection of Broad Street and Market Street (then known as High Street) where it now stands, preferring instead that it be built in Washington Square, near Independence Hall. Lea believed that the project cost too much, and he was angered by the political corruption involved in the awarding of contracts and purchase of building materials for the project. Lea planned and held a large public meeting to recruit support for his alternative to the Penn Square project.