Why do we say "A penny for your thoughts"?

Meaning:

What are you thinking about?

Background:

Once again, it seems that the prolific John Heywood, and his 1546 book of proverbs, are responsible for this expression.

Heywood was a 16th century English dramatist employed at the courts of first Henry VIII and then Queen Mary, as a singer, musician and playwright. When the Protestant Elizabeth I succeeded to the throne in 1564, Heywood (a Roman Catholic) fled to Belgium where he stayed for the rest of his life. He is considered important to the development of English comedy and is also remembered for his epigrams, proverbs and ballads.

More expressions and their source

Challenge yourself with BookBrowse Wordplays