Modelling, a polysemous idea and all but universal practice in the sciences, is essential to computing and therefore helpful in understanding the implications and consequences of humanities computing for the disciplines in its purview. As defined by their principal application in the physical sciences, models are crude, manipulable simplifications whose heuristic power comes both from the insight they give into otherwise inaccessible aspects of the world and from what they fail to capture. They are thus tools for knowing true things by what their mockeries be.