“This work by the great physicist will be found to possess an abiding charm and an intellectual stimulation.”-Observer.

“Opens up new views into the nature of the universe. Precise and lucid, it summarises our knowledge of the substance which fills all space and penetrates all matter—the substratum of matter itself.”—Birmingham Post.

Please write for announcements and descriptive list:

Harper & Brothers, 45 Albemarle Street, London, W.

Harper’s Library of Living Thought

Foolscap 8vo, gilt tops, decorative covers, richly gilt backs
Per Volume: Cloth 2s. 6d. net. Leather 3s. 6d. net.

PROF. ARTHUR KEITH, M.D.
(Hunterian Professor Royal College of Surgeons)
ANCIENT TYPES OF MAN
Illustrated

“The kind of book that only a master of his subject could write. It must interest every thinking person.”—British Medical Journal.

PROF. FREDERICK CZAPEK
CHEMICAL PHENOMENA IN LIFE

Discusses in clear, concise terms the great question—“Can life be explained by physics and chemistry?” It deals with the life-processes of plants, the molecular structure of protoplasm, organic synthesis in the cell, the nature of ferments, and the subject of inheritance.