Conspicuously absent:<p>&quot;you can scarcely imagine how expensive our text books are.  Having tried to save some money through the purchase of a second-hand edition of Euclid&#x27;s Elements, I am at risk of failing that class.  The only change is that for this year&#x27;s edition for some reason all the postulates have been renumbered, making it impossible for me to use the text in class.&quot;