Structural understanding and design
In the beginning, there was probably a large measure of simple trial and error in which pure chance could have played a major part. Nevertheless it would have been possible to conceive prototypes of forms like those illustrated in Figures 1.1 and 7.1 ab initio on the basis of no more than the simplest of the spatial or geometric requirements for stable equilibrium discussed in Chapter 2, and it seems virtually certain that they would have been thought of in these terms once built. This is not to say that these requirements could then, or would then, have been explicitly formulated, any more than they are formulated today by the average child playing with small blocks on the floor. They would rather have been intuitively apprehended in a dual recognition of the tendency of every object to fall and the possibility of preventing the fall by placing an obstacle in its way.