By examining the individual colors of each ray, you can see a purpose for each. This allows you to see the energy impact that each ray has on you.
Black and White are considered different from the colored rays since they represent the energy impact and its content. These impacts can be seen as different shades of the color Gray (the combination of Black and White). Your frame of mind is affected by the amount of Black or White impact that you receive. Everyone has Black and White energy in and around them, but only through balance can the impact of a perfect shade of Gray be experienced.
In the illustration below, you can see the seven colored rays and the different shades of Gray energy impact (combination of Black and White) that fills them.