Aristotle defines growing as a process in which an individual living being persists as it accumulates new matter. This definition raises the question of what enables an individual to persist as its material composition continuously changes over time. This paper provides a systematic account of Pietro Pomponazzi’s answer to this question. In his De nutritione et augmentatione, Pomponazzi argues that individuals persist in virtue of their forms. Forms are individuated in part by their material, causal, and temporal origins, which commits Pomponazzi to the view that individuals necessarily have the material, causal, and temporal origins they do. I provide an account of why Pomponazzi held this view. While his opponents remain unnamed, I argue that his arguments for this view are best read as addressing, among others, Paul of Venice and Gregory of Rimini.