It is well known that the equation E = mc is a consequence from the Theory of Relativity. Little known, however, is that there is also a simple demonstration of this relation by Einstein derived from the laws of classical physics. This was the first step on an alternative path leading to relativity. Ignored for more than a century, this new approach is now investigated with the present work. It is shown that the Principle of Equivalence of Mass and Energy in connection with Newton's Second Law of Dynamics allows a logical and intuitive transition from Newtonian to Relativistic Mechanics. The book "Newton and Relativity" illustrates the surprising results of this research. The authors: Dr. Ing. Francesco Cester Dr. rer. nat. Manfred Clemente Dr. rer. nat. Hans-Michael Korff E-Mail: NewtonAndRelativity@gmx.de