ABSTRACT
The construction of a model, therefore, was for him a miracle of equilibrium between principles (left in shadow) and experience (elusive), but the result should be more substantial than either. In a well-made model, in fact, every detail must be conditioned by the others, so that everything holds together in absolute coherence, as in a mechanism where if one gear jams, everything jams. A model is by definition that in which nothing has to be changed, that which works perfectly; whereas reality, as we see clearly, does not work and constantly falls to pieces; so we must force it, more or less roughly, to assume the form of the model.
