The present book is intended, as far as possible, to give an exact insight into the theory of
Relativity to those readers who, from a general scientific and philosophical point of view, are
interested in the theory, but who are not conversant with the mathematical apparatus of
theoretical physics. The work presumes a standard of education corresponding to that of a
university matriculation examination, and, despite the shortness of the book, a fair amount
of patience and force of will on the part of the reader. The author has spared
himself no pains in his endeavor to present the main ideas in the simplest and most
intelligible form, and on the whole, in the sequence and connection in which they actually
originated. In the interest of clearness, it appeared to me inevitable that I should
repeat myself frequently, without paying the slightest attention to the elegance of the
presentation. I adhered scrupulously to the precept of that brilliant theoretical physicist L.
Boltzmann, according to whom matters of elegance ought to be left to the tailor and
to the cobbler. I make no pretence of having withheld from the reader difficulties which
are inherent to the subject.