Optician more important and dignified. Far-sighted or aging colonial Americans imported spectacles from Europe. Spectacles were primarily for the affluent and literate colonists, who required a valuable and precious appliance. Benjamin Franklin in the 1780s developed the bifocal. Bifocal lenses advanced little in the first half of the 19th century. The terms bifocal and trifocal were introduced in London by John Isaac Hawkins, whose trifocals were patented in 1827. In 1884 B. M. Hanna was granted patents on two forms of bifocals which become commercially standardized as the "cemented" and "perfection" bifocals. Both had the serious faults of ugly appearance, fragility,
Letter to M. D'Alembert on Spectacles is to make sure a society's women are in order. Rousseau believed that public morals could be created not by laws or punishment, but simply by women, who have access to their senses and largely control the way men think. He praised Geneva for its moral women, and its ordered familial sphere, while criticizing the women of the salons in France for making men womanly and cowardly. In post-modern thinking, there has been renewed interest and appreciation for Rousseau's "Letter to M. D'Alembert on Spectacles", with the acceptance since Rousseau's time of utopian and primitivist elements in political thought. Rousseau's