As Ashby and Lee¹ recently pointed out, there is a great deal of trial-by-trial variability in all perceptual representations. However, stability is the first apparent visual concept of the world to which we have adjusted. Although proximal stimulation is continuously changing, our phenomenal world is usually stable, made up of objects which usually remain the same size, shape, colour and identity. The second aspect is harmony. Very often, objects in nature keep a specific regular and harmonic structure. It is interesting to note that we are particularly pleased when we find such regularity and harmony. Almost perfect beautiful examples of axial or central symmetry can be found in the inanimate world as well as in the biological world. These are often considered conclusive evidence that natural phenomena conform to natural laws. At the same time, the pleasure that we experience in perceiving regular and harmonic configurations (and the tension that we feel when we face configurations that depart from this regularity and harmony), is considered conclusive evidence of the fact that perceptual organisation is dominated by the tendency to Prägnanz. Therefore, this tendency can be considered the leading principle that governs perception.