Change, motion, and explanation › Making change intelligible

In Book I, Aristotle examines arguments that make coming-to-be appear impossible. If something comes from what already is, why call it coming-to-be? If it comes from what is not, how can nothing produce something? His response distinguishes the underlying subject from the character it acquires and the character it previously lacked (Physics I.7–8).

His example is a person becoming musical. The person persists, but being unmusical does not persist as the resulting condition. We can therefore distinguish what undergoes the change from the description under which it changes. The musical person comes from someone who was not musical, without coming from absolute nothing. A determinate lack is different from the absence of any subject (Physics I.7–9).

This needs qualification when we consider substantial generation rather than a change in someone's skill. A new living thing does not simply mean that an already complete individual has acquired another incidental property. Aristotle's inquiry must explain coming-to-be as well as alteration. The distinction between an underlying material basis and an acquired form supplies his framework for addressing these cases, without implying that the same organized individual survives every kind of change.

For a contemporary analogy, consider clay being made into a bowl. The clay is not nothing before the bowl exists, but neither is it already an actual bowl. Saying it is capable of becoming a bowl identifies a possibility grounded in the material and the circumstances. It does not imply that every possible object is already hidden inside the clay, waiting to be uncovered.