Therefore, although the statement "mass equals energy" is not difficult to say, it does not imply that it is easy to understand, since there is no knowledge in the words per se. There is a difference between the description and the object being described. When one says, "I cannot describe how to do it", one often means that one cannot describe it sufficiently for someone else to fully understand it or be able to do it, since understanding requires familiarity with both the concepts themselves and the context to which they normally belong. Hence,