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. On the other hand, I have purposely treated
the empirical physical foundations of the theory in a step-motherly
fashion, so that readers unfamiliar with physics may not feel like the
wanderer who was unable to see the forest for the trees. May the book
bring some one a few happy hours of suggestive thought!
December, 1916
A. EINSTEIN
PART I: THE SPECIAL THEORY OF RELATIVITY
I.
PHYSICAL MEANING OF GEOMETRICAL PROPOSITIONS
In your schooldays most of you who read this book made acquaintance
with the noble building of Euclid s geometry, and you remember perhaps
with more respect than love the magnificent structure, on the lofty
staircase of which you were chased about for uncounted hours by
conscientious teachers. By reason of our past experience, you would
certainly regard everyone with disdain who should pronounce even the
most out-of-the-way proposition of this science to be untrue. But
perhaps this feeling of proud certainty would leave you immediately if
some one were to ask you: What, then, do you mean by the assertion
that these propositions are true? Let us proceed to give this question
a little consideration.
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