"Even though the Lorentz theory is no longer generally accepted today, it is worthwhile to study it in some detail, not only because it helps to provide an appreciation of the historical context out of which the theory of relativity arose, but much more because it helps us to understand the essential content of Einstein’s new approach to the problem. Indeed, a critical examination of the Lorentz theory leads one, on the basis of already familiar and accepted physical notions, to see clearly what is wrong with the Newtonian concepts of space and time, as well as to suggest a great many of the changes needed in order to avoid the difficulties to which these concepts lead. Lorentz began by accepting the assumption of an ether. However, his basic new step was to study the dependence of the process of measurement of space and time on the relationship between the atomic constitution of matter and the movement of matter through the ether."