Solomon Northup was born a free man in Saratoga Springs, New York, in 1808. He lived as such until 1841 when, attracted by a job offer, he travelled to Washington, DC, where he was drugged and sold into slavery by his supposed employers.

Northup was enslaved for twelve years before he regained his freedom and returned to New York. There, he became an advocate for abolitionism and in the 1860s began helping fugitive slaves via the Underground Railroad.

Northup is believed to have died between 1863 and 1875, but both the date and circumstances of his death are unknown.

Tom Butler-Bowdon is recognised as an expert on personal development literature.

His 50 Classics series has been hailed as the definitive guide to the literature of possibility, and has won numerous awards including the Benjamin Franklin Self-Help Award and Foreword Magazine's Book of the Year Award.

A graduate of the London School of Economics and the University of Sydney, he lives and works in both the Oxford, UK and Australia.