"Galileo explicitly criticized the current practice of using small scale models to design buildings and machines, because he believed that they could provide only mechanical information, regardless of scale. The Galilean critique of the practice of using models is directed at those who were convinced as to the usefulness of models, whether architectural or sculptural, that faithfully reproduced form without paying attention to the differences between the materials used in the model and those used in the actual object. Alberti strenuously defended the use of models; he was the first after Vitruvius to list their advantages (as did Baldinucci) while, however, specifically excluding their use as instruments for determining the strength of a structure or any of its parts.

Alberti expressed the concept that the design is fixed in the mind that elaborates it; its form is invariable because it is independent from the material in which it is to be realized. In actual practice, of course, things are not exactly as Alberti presents them, because forms are determined by numbers and dimensions; one cannot simply ignore the importance of the factor of the weight, except perhaps during the initial formulation of the problem, and only then as long as the scale of the model is not too small with respect to the object to be realized. On the other hand, it is very probable that Alberti was codifying a design practice used in medieval workshops where models, due to their particular architectonic forms, were used to resolve problems of stability, if not of strength. As we shall see in this paper, the model of Brunelleschi's design for the Florentine cupola appears to have served this purpose."