Three principles of garden design apply to the overall "feel" of the landscape: namely, proportion, transition and unity. Landscape plants should be arranged so as to conform to these principles. Proportion is the sense that the size of the individual components (the landscape plants) or groups of components in a landscape is consistent with the landscape as a whole. In other words, the idea behind proportion is very similar to that behind the basic element, scale. But the difference is that, while "scale" is a neutral term, "proportion" is based on the premise that something is either "in proportion" or "out of proportion." A garden design that is out of proportion is one that is marred by abrupt transitions or by the lack of transition. For instance, a five-foot-high stone wall might elegantly set off a large home but would make a small home look all the smaller. The landscaping of the latter suffers from a lack of transition: the height of the wall is too close to that of the house. Transition, simply put, refers to gradual change.