WHETHER this book is ‘modern’ in the good sense or the bad sense of that irritating word is for the reader to judge. I have tried to produce an ethical theory which should be both impregnated by the polliniferous wind of contemporary thought, and yet not without roots in the past. But since the roots do not appear above the ground, I may perhaps be charged with ignoring much ancient and invaluable wisdom, and lending an uncritical ear to modern jargon. There may be some truth in such a charge, since to attend closely to one thing entails a corresponding neglect of others. My chief aim has been to consider a distinctively modern and urgent, though theoretical, problem; and, through concern with the modern, I may perhaps seem to have been unduly silent about Greece and Palestine.