Reciprocal Symmetry and Equivalence between Relativistic and Quantum   Mechanical Concepts
  We have defined slowness (or reciprocal velocity) corresponding to v as cc/v, where c is the speed of light and v is the corresponding velocity. Velocity and slowness are images of each other. Reciprocal symmetric law of addition of velocities fulfils the requirement that the sum (or the difference) of velocities remains unchanged if velocities are replaced by the corresponding slownesses. We have postulated reciprocal symmetry, which states that every valid statement has an equally valid (reciprocal) image statement. The postulate has allowed us to derive: (1). Relativistic law of addition of velocities from Einstein's image postulate that no physical body can travel with a slowness less than the slowness of light. (2). Black body radiation formula from Planck's image postulate that no body can attain a level of energy higher than an upper limit value 2W. 
Mushfiq Ahmad