Nisbet asserts there are two fundamental building blocks necessary to Western doctrines of human advancement: the idea of growth, and the idea of necessity. He sees Christianity as a key element in both secular and spiritual evolution, for it conveys all the ingredients of the modern idea of progress: the advancement of the human race in time, a single time frame for all the peoples and epochs of the past and present, the conception of time as linear, and the envisagement of the future as having a Utopian end.
In his new introduction, Nisbet shows why the idea of progress remains of critical importance to studies of social evolution and natural history. He provides a contemporary basis for many disciplines, including sociology, economics, philosophy, religion, politics, and science. History of the Idea of Progress continues to be a major resource for scholars in all these areas.