In fact, for a plate of circular shape, resting in the centre (or the border, or at least in a set of points with central symmetry), the nodal vibration modes all have central symmetry, so the observation of Jenny is entirely consistent with well known mathematical properties. From the physical-mathematical standpoint, the form of the nodal patterns is predetermined by the shape of the body set in vibration or, in the case of acoustic waves in a gas, the shape of the cavity in which the gas is contained. The sound wave, therefore, does not influence at all the shape of the vibrating body or the shape of the nodal patterns. The only thing that changes due to the vibration is the arrangement of the sand. The image formed by the sand, in turn, is influenced by the frequency spectrum of the vibration only because each vibration mode is characterized by a specific frequency. Therefore, the spectrum of the signal that excites the vibration determines which patterns are actually nodally displayed. The physical phenomena involved in the formation of Chladni figures are best explained by classical physics. Modern analysts, including Michael Shermer, have termed anthroposophy's application in areas such as engineering, medicine, biology, and biodynamic agriculture as pseudoscience.