 While both the geologist and the historian are concerned with the past, the questions that they ask and the presuppositions which give rise to those questions are different. Scientific inquiry rests on the presupposition of the uniformity of nature. This principle is required to formulate the inductive hypotheses which enable empirical scientists to predict what will happen in the future and retrodict what happened in the past. Empirically minded scientists presuppose that everything that happens is subject to natural laws which are invariant over time, for example, that water freezes at 0° Celsius under the reign of Queen Victoria as well as the time of Henry VIII. But while this presupposition is well suited to serve the explanatory goals of natural science, it is of limited use to historians who are concerned not with what is invariant throughout history, but with what is distinctive about different periods of time. It would not help an Egyptologist to understand the rituals of the ancient Egyptian to ascribe them the mindset of a medieval feudal baron. As Collingwood puts it: