Thank you for finding it. I was interested in seeing how difficult the problems were. The first page does seem it requires knowledge of calculus and partial derivatives. The problems he referred to are of the &quot;Examples for Solution&quot; kind like the one on page 3. For motivation, Dyson also said &quot;The difference between a text without problems and a text with problems is like the difference between learning to read a language and learning to speak it. I intended to speak the language of Einstein, and so I worked my way through the problems. I started at six in the morning and stopped at ten in the evening, with short breaks for meals. I averaged fourteen hours a day. Never have a I enjoyed a vacation more.&quot;