Unawareness Quotes
Although most listeners had to spend some time parsing this famous quote, it actually was not a new notion. See Copernicus in linked quotes.
This is the source of the proverb, “Ignorance is bliss.”
Cryptocporidium is an illness caused by parasites in drinking water. It has been known about since 1974, but when the EPA set standards for drinking water under the Safe Drinking Water Act, but did not include Cryptocporidium.