Problems of Life and Mind. 5 volumes complete, all first editions. First Series: The Foundations of a Creed Vol. I. [II.] 1874/5; Second Series: The Physical Basis of Mind, 1877; Third Series Part I: The Study of Psychology, 1879; Part II: Mind as a Function of the Organism, The Sphere of Sense and Logic of Feeling, The Sphere of Intellect and Logic of Signs. 1879.

Five volumes octavo in original publisher's red brown cloth: xiii, [3], 472; viii, [2], 542; viii, 189; xiv, [2], 493; x, 500pp. Overall good copies with a few minor defects: the 2nd volume has the front inner hinge neatly stenghthened, label is missing from 4th volume, and label of 5th volume is damaged. Lewes's magnum opus, unfinished at his death, the last volume being published posthumously. He proposes a scientific psychology which incorporates both the objective study of the mind and the subjective study of consciousness practiced in philosophy. Lewes's varied interests are reflected in the wide-ranging scope of this work which occupies an important place in the history and philosophy of science in the 19th century. Complete sets such as this are rare.