[T]heology is, for all its modesty, in an exemplary way a free science. This means it is a science which joyfully respects the mystery of the freedom of its object and which, in turn, is again and again freed by its object from any dependence on subordinate presuppositions.In modern usage, science is the study of a particular object or range of objects. Physics takes as its objects the most basic or "fundamental" objects of the empirical world, e.g. particles, energy, forces. Biology takes as its objects all living things, though it is not at all times clear what this means. Economics may take as its object particular markets, e.g. the housing market or the automobile industry, or it may take that grand object which Hayek liked to call the "catallaxy." In all cases, the amount of knowledge we can obtain about something is often inversely proportional to the level of complexity with which we are dealing. This is how it is usually described: physics studies the most simple objects, chemistry studies one level of complexity higher (i.e. compounds of the most basic materials), biology studies another level, psychology and neuroscience perhaps another level higher, environmental science and ecology another level still, and finally the social sciences: sociology, economics, and political science.
--Karl Barth, Evangelical Theology: An Introduction
If we can classify mathematics as a science, it precedes even physics on this staircase of complexity. As John von Neumann said, "If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is." Mathematicians study the very simplest objects of all: those which can be defined precisely and axiomatically, and which therefore can be understood with absolute certainty.