Mixis and Diagnôsis: Aristotle and the "Chemistry" of the Sublunary World

In On Generation and Corruption 1.10, Aristotle introduces the new idea of "chemical mixture" (mixis) to explain the constitution of those homogeneous substances from which all things in the sublunary world are comprised. In a mixture, the ingredients interact with one another to give rise to a new substance, qualitatively different, yet preserving the original ingredients in potentia, so that they can be separated again. In Book IV of the Meteorologica, Aristotle further suggests that bodies may be "diagnosed" according to certain passive properties, such as the fusibility of metals. While his theory of mixture has often led historians of science to identify Aristotle as one of the precursors of chemical science, his ideas have also been criticised as archaic, and implicated in a qualitative conception of the cosmos that delayed progress towards quantifying natural phenomena. In this paper, I take up the defence of Aristotle's theory by showing that his concept of mixture is not an obstacle to the development of natural science and chemistry, but, on the contrary, opens the way by offering an advanced model of qualitative analysis which does not exclude the possibility of quantitative development.