Science is a multifaceted, natural and historical phenomenon. It consists of five elements, that is, it happens in five distinct media: biological, linguistic, technological, social, and historical. None of these alone provides an indubitable basis for the truth of scientific knowledge, but combined together they compose a solid ground for our trust in its reliability. The composition, however, is uniquely related to our modern mode of living. Science did not exist before modernity, and it will cease to exist in this form if our way of life should change. The book presents a thorough analysis of all these dimensions and their relations, and thus lays the path for an integral theory of science. Because of this it can be used as a textbook for general courses in the theory of science at both the undergraduate and graduate level.