Slovenly Peter, originally published in 1845 Germany as Der Struwwelpeter, is authored by Frankfurt physician Heinrich Hoffman. He wrote the book because there were no effective cautionary tales that would teach good behavior to his 3-year-old son. Hoffman was clearly not a child psychologist, although his bedside manner was typical of his period in medical circles.
The first English translation was published in 1848. Then many decades later, the American author and humorist Mark Twain translated the book and gave it to his three daughters in 1891. That version was published in 1935. Thanks daddy!!
The ten cautionary tales featured within are rhymes accompanied by vivid illustrations of boys and girls in nightmarish scenarios. Some might call them grim or Grimm!?). The illustrations depict the dire consequences of such disobedient and nasty behaviors as poor hygiene, cruelty, playing with matches, bullying, thumb sucking, eating poorly, fidgeting at the table, and not paying attention while walking (almost none of them applies to me). While I read that many German parents today find the tales disturbing, those who raised their "kin during the early decades of the 20th century found them useful for childrearing" (think 1933 and thereafter). Mention of this or that character in Der Struwwelpeter served as coded criticism of objectionable behavior (think the initials DJT).
What happens to disobedient children who suck their thumbs when told not to, for instance, is illustrated in four panels. In the third, the orally fixated protagonist's thumbs are about to be cut off by the tailor because he did not listen to his mother. Another warning, rather progressive at that, was for "bullying a boy of color," the bullies are dipped in ink.
The book can be compared to other proscriptive stories from different periods, nationalities and cultures. I wonder how children reacted to Der Stuvwwelpeter — a little scared or major trauma?