id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
hindsight-3620	Editors, Hindsight	Vol 21, No 4 (1990)	1990	12	.pdf	application/pdf	4974	203	51	The author's philosophical springboard is his division of practical optical history into three undulatory periods, - - - scientific, unscientific, and scientific, identified approximately with, (1) the Moors and early Western opticians, (2) the rule-of­ thumb era of optical craftsmen, and (3) the age of scientific research as exemplified by Fraunhofer (1787-1826). Optometry and world history:	cache/hindsight-3620.pdf	txt/hindsight-3620.txt