DOCTOR MARCOS MOSHINSKY AND THE AUTHOR HAVE BEEN INDEPENDETLY INTERESTED IN THE SUBJECT. RECENTLY, DOCTOR MOSHINSKY HAS SHOWN THE EQUIVALENCE BETWEEN HIS OWN TREATMENT AND THE AUTHORS.OUR METHOD IN THIS PROBLEM IS ESSENTIALLY BASED ON MINKOWSKIS SPACE- TIME GEOMETRY ANDE FRESNELS INTUITIVE TREATMENT OF DIFFRACTION. IN THIS WAY, THE FUNDAMENTAL FORMULAS OF WAVE MECHANICS COME OUT WITH A COMPLETE SYMMETRY BETWEEN SPACE AND TIME, AND FEYNMANS INTERPRETATION OF NEGATIVE ENERGY STATES IS VERY CLEARLY ILLUSTRATED.