The essays, initially published in the English periodical The Nineteenth Century between 1890 and 1896, explore the role of mutually-beneficial cooperation and reciprocity (or "mutual aid") in the animal kingdom and human societies both past and present. It is an argument against theories of social Darwinism that emphasize competition and survival of the fittest, and against the romantic depictions by writers such as Jean-Jacques Rousseau, who thought that cooperation was motivated by universal love. Instead Kropotkin argues that mutual aid has pragmatic advantages for the survival of human and animal communities and, along with the conscience, has been promoted through natural selection.