care killed the cat 这句话为什么是忧虑伤身的意思？有什么典故吗

There is an older form of this expression that goes: "Care killed the cat." The word 'care,' in this case, seems to be defined as "worry" or "sorrow." This form of the expression goes back to at least the 16th century. It's used by a few playwrights (剧作家)during that time. For example, an English playwright named Ben Jonson is said to
have used it in a play called Every Man in His Humour, 1598. Another playwright,William Shakespeare, used the expression in the play Much Ado About Nothing, which is thought to have been written in 1599:
"What, courage man! what though care killed a cat, thou hast mettle enough in thee to kill care."
The earliest that I could find of the modern phrase being used in writing is from a book by James Allan Mair called Proverbs and Family Mottoes, 1891, where it's simply listed as a proverb on one of the pages:
"Curiosity killed the cat."

cat可以忽略，很多对人的都用猫说话，比如curiosity kills the cat.好奇害死猫