>I had a calculus book once that said, 'What one fool can do, another can.'
A link to a pdf file of a copy of an old calculus book from early nineteen-hundreds showed up on HN a week or so ago. I read the first couple of pages. That quote is likely referencing that particular book. I have lost the link now. Anyone remember?
Edit: sry, that was weak Googleing from my part. Here it is: http://djm.cc/library/Calculus_Made_Easy_Thompson.pdf