Of these essays, “Progress” has already appeared in the _Hibbert Journal_, “Biology and Sociology” in the _Monist_, “Ils n’ont que de l’âme” and “Philosophic Ants” in the _Cornbill Magazine_, “Rationalism and the Idea of God” in the _Rationalist Press Annual_, and “Religion and Science” in _Science and Civilization_, this year’s representative of the annual “Unity” series edited by Mr. F. S. Marvin and published by the Oxford University Press. They have all, however, been considerably revised and enlarged before appearing in the present volume. I have to thank the proprietors and publishers for kindly permitting me to reprint these. OXFORD, _April 1923_. CONTENTS I PROGRESS, BIOLOGICAL AND OTHER 3 II BIOLOGY AND SOCIOLOGY 69 III ILS N’ONT QUE DE L’ÂME: AN ESSAY ON BIRD-MIND 107 IV SEX BIOLOGY AND SEX PSYCHOLOGY 133 V PHILOSOPHIC ANTS: A BIOLOGIC FANTASY 177 VI RATIONALISM AND THE IDEA OF GOD 207 VII RELIGION AND SCIENCE: OLD WINE IN NEW BOTTLES 235 I PROGRESS, BIOLOGICAL AND OTHER EVOLUTION: AT THE MIND’S CINEMA I turn the handle and the story starts: Reel after reel is all astronomy, Till life, enkindled in a niche of sky, Leaps on the stage to play a million parts. Life leaves the slime and through all ocean darts; She conquers earth, and raises wings to fly; Then spirit blooms, and learns how not to die,-- Nesting beyond the grave in others’ hearts. --I turn the handle: other men like me Have made the film: and now I sit and look In quiet, privileged like Divinity To read the roaring world as in a book. If this thy past, where shall thy future climb, O Spirit, built of Elements and Time! MUNICH, _Jan. 1923_. PROGRESS, BIOLOGICAL AND OTHER “Usus et impigrae simul experientia mentis Paulatim docuit pedetemtim progredientes.” --LUCRETIUS. “As natural selection works solely by and for the good of each being, all corporeal and mental environments will tend to progress towards perfection.” --CHARLES DARWIN. “Social progress means the checking of the cosmic process at every step and the substitution for it of another which may be called the ethical process.” --T. H. HUXLEY. “It is probable that what hindered Kant from broaching his theory of progress with as much confidence as Condorcet was his perception that nothing could be decisively affirmed about the course of civilization until the laws of its movement had been discovered. He saw that this was a matter for future scientific investigation.” --J. B. BURY.