Throughout section 3 we have realized that the spatial contractions can be materialized as forces of the fields. This fact can be interpreted from two different points of view in the System of the Symbol.

The first point of view is based on the consideration that the angular forces present in each position of Edgeworth’s Box, true field of associated angular factors, contract the space.

The second point of view is based on the consideration that the angular forces which are detected in each position of the Edgeworth’s Box are products of the spatial contraction.

The first standpoint is Newtonian and the second is Einstenian, but whichever is considered the true one, the practical result is the same: Edgeworth’s Box contains a third dimension, not perceptible at first glance, but it appears when the System’s logical - mathematical is driven to its ultimate end.

In section 3.5 "Structural contraction factors" we saw that in three dimensions the contraction factor is 50% (factor = 0,5). If this is applied to the figure deducted in section 3.2 "Construction of a field of associated angular factors", in which in the third dimension appears a figure like a "archbishop’s mitre", we’ll conclude that the addition of volumes of the two tetrahedrons of the mitre should be equal to the half of the volume of a cube which has as basis the angular plane contained in the Edgeworth’s box, and this is so if its checked up with geometrical calculations.

On the other hand, the picks of the two tetrahedrons of the Mitral figure are situated in the vertical of the coordinates 0,25 / 0,25 AB+ and 0,25 / 0,25 AB-, as in both cases the addition of the two forces expressed in angles is the minimum possible, and hence the Hamilton’s principle will make preferential the movements of the projections of the graphs towards those verticals.

In consequence, the projection of the evolution of the successive states of any curve or graph on the Edgeworth’s Box, will tend to move towards the 0,25 / 0,25 coordinates, as if a geodesic force would act upon those projections, which in the system of the Symbol is named MITRAL FORCE.

Likewise, in the main falling tendencies, when a graph gets ways, falling further, it’s being subjected to a "geodesic force" or MITRAL FORCE which tends to get it rising (attracting the chart from below), towards the main tendency. The graph can only keep away from the main tendency line if "continuous pulling down impulses" are produced, neutralizing that geodesic force.

Given that tendencies either rising or falling , represent the environment where the graphs deploy (falling, rising and neutral environment) which tends to attract towards itself the future evolution of the graphs, the MITRAL FORCE, angular expression of the effect of the tendencies. This force will represent the FORCE OF ENVIRONMENT, and for this, in the system of the Symbol, the MITRAL FORCE is identified with the force of the milieu or environment, as it is a "natural" move towards which the projection of a graph under a determined tendency goes.

In these conditions we say that if the addition of the two current angular coordinates are bigger than the addition of the two angular coordinates in a future position of the graph, the environment favours or endorses the move towards that possible future. On the contrary, if the addition of the two current angular coordinates are smaller than the addition of the two angular coordinates in a future position of the graph, the environment opposes to the move towards that possible future. In the first case we will achieve that future almost effortless and in the second we’ll have to endeavour decidedly.

The degree of effort of the environment, for and against, can be measured and the system of the Symbol does it, conceptually, subtracting to the biggest addition of the coordinates the smallest addition of coordinates of the comparing position. This figure is then translated into a percentage.