The earliest known examples of Lincoln's handwriting come from the arithmetic text that he copied out for his own educational use while living in Indiana. His later law partner and biographer, William H. Herndon, acquired the hand-stitched notebook in 1866. The leaves were later separated and scattered, and today only ten of them are located. It was a fitting addition to the collection of George Arthur Plimpton, a member of the board of directors of textbook publishers Ginn & Company, whose vast collection shows the development of education.