A chain reaction that occurs when a small change causes a similar change nearby. This on in linear sequence like a line points are.The shadows in the picture show the same as the dominoes do. If the first one of dominoes has fallen, we know the last one has also fallen when the case like in the photo. When calculating we know one value of something and so we know the values of other values on the same curve. The above refers the similar cases found at a common curve. Phenomena and products belong on their own curves. Even things being on same curve is not necessary, but of this later. In the photo dominoes form an example of the curve.
The told Plato Cave Metaphor was formed of the concrete reality which casted the shadows on the cave wall, but there are shadows in many forms. When a beam has a load on, it has a measurable shadow as a defleftion. The shadow tells the needed of the beam. When an athletic run, there is a shadow in form of the time. The used time tells the needed of the event.
The calculation is more interested in physics and product formation, although no human can not be left outside. The following is an example of a curve which products and phenomena show of their values.