The Einstein formula: E_0=mc^2 "Isn't the Lord laughing?"
  The article traces the way Einstein formulated the relation between energy and mass in his work from 1905 to 1955. Einstein emphasized quite often that the mass $m$ of a body is equivalent to its rest energy $E_0$. At the same time he frequently resorted to the less clear-cut statement of equivalence of energy and mass. As a result, Einstein's formula $E_0=mc^2$ still remains much less known than its popular form, $E=mc^2$, in which $E$ is the total energy equal to the sum of the rest energy and the kinetic energy of a freely moving body. One of the consequences of this is the widespread fallacy that the mass of a body increases when its velocity increases and even that this is an experimental fact. As wrote the playwright A N Ostrovsky "Something must exist for people, something so austere, so lofty, so sacrosanct that it would make profaning it unthinkable." 
L.B. Okun