“When psychical phenomena have been as much investigated as physical, love will also receive its cumatology - that is, its science of waves. We shall follow the curves of the emotions through the ages, their movement of rise and fall, the oppositions and side-influences by which they have been determined.”

Swedish writer and social thinker

Ellen Key was a Swedish writer and social thinker associated with the Modern Breakthrough movement. She lived from 1849 to 1926 and wrote on family life, ethics, education, and women's rights. She is especially remembered as an early advocate of child-centered education and parenting. Her work also placed her among the women’s suffrage advocates of her time, and her writing often returned to questions of home, moral life, and how society should shape the next generation.