First of all, apples were not always sweet. They were bitter and sometimes even poisonous. They were, however, very popular and useful in the form of hard cider, as water was considered more dangerous to drink. However, after a movement of “anti-alcohol fervor” swept the nation in the late 19th Century, the apple seemed doomed. If it were not for some early, innovative public relations, promoting the apple as “healthy food-stuff,” it may have never recovered. The slogan “an apple a day keeps the Doctor away,” gave a new “social respectability” to the fruit, encouraging growers to develop sweet, edible varieties.
“Held up as the paragon of moral fastidiousness, teachers, particularly on the frontier, frequently received sustenance from the pupils.” Even when that was no longer common practice, an apple for the teacher was used to “curry favor.” Hence the term, “apple-polisher” being short for brown-nosing suck up. (ref: Smithsonian.com)
How about them apples?