ABSTRACT
It was an exceptionally warm and beautiful May Sunday.1 Finally, a nice stretch of free time, after working all week at the Bern Patent Office! Since that morning, Albert Einstein had been enjoying the opportunity to spend an entire day thinking about the scientific problem that had been obsessing him for years. Not that he thought of it ceaselessly-far from it! Indeed his thoughts had been quite busy with other research for the first few months of 1905.
