[Homer_J_Simpson]

They knew that boiling clothes and sheets would kill vermin and reduce disease, but they didn't know that boiling also kills germs in water or on surfaces.

The failure of medical science of the time to make that connection would cost the Lincoln family a son a few years later.

[Tax-chick]

That was very sad. They were so close: they even recognized that tea and coffee were safer than water, but they thought it was the tea or coffee plants, rather than because the beverages were made with boiling water.