Just when it seemed we’d heard—and seen—everything there is to know about one of America’s most prolific and portrayed Presidents, two vital, long-lost relics from his past, one verbal and one visual, have unexpectedly surfaced.

For years scholars have known that Lincoln penned some sort of letter in the fall of 1859 to the Ohio orator and Republican senator Thomas Corwin. Two surviving Corwin letters to Lincoln neatly bracket, and indisputably attest to, the missing communication. In the first, Corwin chides Lincoln for allegedly saying in a Cincinnati speech that a moderate Republican presidential candidate would lose Illinois by 50,000 votes in 1860. In the second, written nearly a month later, Corwin notes, “I have red [received] your explanation,” adding: “Six months hence we shall see more clearly what at this time must remain only in conjecture.”

But what had Lincoln written to Corwin in between? All that the Library of Congress’s Abraham Lincoln Papers Web site offered was the notation “The ‘explanation’ referred to has not been located.”

Now it has. About a year ago the Abraham Lincoln Book Shop in Chicago announced that it had been brought a three-page handwritten “Confidential” note, long quietly treasured by Corwin’s descendants. Undeniably Lincoln’s, it offers some of the strongest language he ever used to defend his party’s opposition to slavery, warning:

“Drop that issue, and they [voters] have no motive to remain, and will not remain, with us. It is idiotic to think otherwise. Do you understand me as saying Illinois must have an extreme antislavery candidate? I do not so mean. We must have, though, a man who recognizes that Slavery issue as being the living issue of the day; who does not hesitate to declare slavery a wrong, nor to deal with it as such; who believes in the power, and duty of Congress to prevent the spread of it.”

One can search high and low in the Lincoln corpus for another use of the word idiotic —or for more electric proof that on the cusp of his nomination to the Presidency he was as strongly committed as ever to keeping slavery at the center of American political discourse until it could be eradicated. Unwilling to focus on safer subjects “upon which the old Whig party was beat out of existence”—“tariff, extravagances, live oak contracts, and the like,” he mocks—Lincoln reiterates that there is only one subject worth discussing: “that Slavery issue.”

After he won the nomination the next year, painters and sculptors descended on his hometown to create depictions of the little-known dark-horse candidate. Lincoln welcomed the artists to his offices in the Springfield statehouse, allowing them to sketch or model him as he opened his daily mail. Most of them had difficulty. Accustomed to sitters who posed in frozen stillness, and frustrated by Lincoln’s requirement that they observe him “on the jump,” several importuned him