In the great reaction of the last century, love, that most cogent motive of human thought and action, fell from its high estate and came to be regarded as an instinct not differing in any essential from hunger and thirst, and existing, like them, from the beginning, eternal and immutable, manifesting itself with equal force in the heart of man and woman, and impelling them towards each other. But Emil Lucka, in his remarkable new book, _The Three Stages of Love_ (which was recently published in Berlin, and has already created a sensation in literary circles abroad), leads us on to speculative heights from which we may look back upon the whole theory of evolution not as a bar but as a bridge. "My book is intended as a monograph of the emotional life of the human race," he says in the preface, and "I am prepared to meet with rejection rather than with approval." There has been abundance of criticism and controversy, but Lucka has stated his case and drawn his conclusions with such admirable precision and logic, that his work has aroused admiration and appreciation even in the ranks of his opponents. Love is a theme which at all times and in all countries has been of primary interest to men and women, and therefore this book, which throws an illuminating ray of light in many a dark place still wrapped in mystery and silence, not only impresses the psychologist, but also fascinates the general reader with its wealth of interesting detail and charm of expression. The three vitally important points which the author develops are as follows:-- Love is not a primary instinct, but has been gradually evolved in historical time. Ernst Haeckel's biogenetic law is expanded in a psychogenetic law. Only man's emotions have undergone evolution, and therefore have a history, while those of woman have experienced no change. Lucka's book will probably not please the advanced feminists, but the delicate, although perhaps involuntary homage to her sex which is implied in his theories ought to rouse a feeling of gratification in the heart of every right-feeling woman. The very limitations and restrictions which he lays upon her raise and glorify her. For while man has been the "Odysseus wandering through heaven and hell, passing from the bestial to the divine to return again and become human, woman has always been the same, unchangeable and without problems. That which he has set up to-day as his highest erotic ideal, the blending of sexual and spiritual love, has been her natural endowment from the beginning. Never perfect, he falls into error and sin where she cannot err, for her instinct is Nature herself, and she knows not the meaning of sin."