[1] The Thinker’s Library was intended as a successor to the cheap paperback “Sixpenny Reprints” from the same publisher, the aim being to bring humanist, philosophical and scientific works to as wide an audience as possible.
[2] Unlike the previous series, the volumes in the Thinker’s Library were small hardbacks (6 ½ x 4 ¼ inches) bound in brown clothette, with grey dustjackets, priced at one shilling.
The covers of the early editions featured title, author’s name and a brief description of the book between Doric columns, with the image of Rodin’s The Thinker at the foot.
The last group included collections of essays by several writers, drama (a volume containing two plays by Euripides), poetry (James Thomson’s The City of Dreadful Night) and memoirs (the Autobiography of Charles Darwin).
The focus was initially on reprints, often abridgements of, or selections from, longer works from well-known free-thinking writers; Darwin, J. S. Mill, H. G. Wells and Herbert Spencer were among those represented in the first ten volumes.