Some mathematicians, like P.S. LaPlace were notorious for omitting a lot of the details in their work. When Nathaniel Bowditch, no slouch when it came to mathematics, undertook to translate LaPlace's 'Celeste Mecanique' into English, he found that the work of the Frenchman was extremely abbreviated, although it took five volumes to print it in the original. Bowditch not only translated LaPlace's work, but he also decided to check all of LaPlace's mathematical derivations himself.
After some time was spent on his project, Bowditch remarked, "Whenever I meet in LaPlace with the words 'Thus it plainly appears', I am sure that hours, and perhaps days, of hard study will alone enable me to discover how it plainly appears."