In all styles of Japanese garden designs careful attention to the shapes and proportions of individual stones is of the first importance. Some teachers of the craft go so far as to maintain that stones constitute the skeleton of the garden, and that their proper selection and distribution should receive primary consideration, the vegetation being disposed in a manner entirely subsidiary to the stone-work. The sizes of the principal rocks and boulders give the scale for the trees, shrubs, fences, lanterns, basins, and other objects placed in proximity to them. Such being the case, great care must be taken to preserve due proportion between the size of stones selected and the area of the garden itself. Large stones would be unsuitable in a small garden, and those diminutive in scale would be out of place in an extensive one. In grounds of considerable area and elaborate design there may be as many as one hundred and thirty-eight principal rocks and stones having special names or functions, in addition to others of secondary importance; but in those of more limited scale and rougher style as few as five stones will often suffice. The principal boulders of a landscape garden are supposed to suggest the mountains, hills, and rocks of natural scenery. It is customary therefore to describe their altitude by fictitious measurements corresponding to the heights of their natural prototypes. This not only helps to keep up the illusion of real landscape, but assists the designer to preserve a consistent character in the subsidiary features.