What are the variable parameters in empty space that define different fields? What has changed in space to alter it from a neutral gravitational field to an electric field? One parameter we have is the speed at which light travels through space. The speed of light is supposedly constant and independent of the observer. But if we change our position from a source of light to another inertial frame of reference, that is a true change in our speed relationship with the speed of that light. It required a force to change from one reference frame to the other and changing our speed relationship. Perhaps a field which causes change in the speeds of light generate forces. My submission is an exercise to demonstrate and establish the changing parameters in space by assuming we can detect these changes in speeds. Following this assumption and a line of reasoning using only elementary principles of physics a picture starts to come into place. A good insight into the inter-relationships of fields is developed. This is an abstract concept which I feel leads to an intuitive and symmetrical interplay between bodies and fields. The concept of primary and non-primary directional space.