Sound advice to Teachers found in מערכת אברהם הדרכה לנערים 1769

In 1769 a curious little book titled מערכת אברהם הדרכה לנערים was published in Fuerth, authored by a school teacher in the Hague, Netherlands, named Avraham Segal. on page יא the author goes on an interesting aside describing how teachers would have bad influence on their students due to being in a fight with his wife:

ולהסיר המכשלה מעבירה גוררת עבירה להיות מחלוקת עם אשתו ומתוך קטטות ומריבות מרבה קללות וארורים. ותלמידיהם הן קטני קטים הן גדולים ונערים שומעים אלו הדברים ולומדים אלו הדברים מכוערים עד שהרגל נעשה טבע..... וכבר צווחו קמאי דקמאי על עושי מלאכתם ברמיה....
 "And to remove the hindrance of having one sin leading to another, that of (the teacher) having a fight with his wife, and through the brawls and fighting with his wife, he frequents curses and swearwords at his students. His students, from the youngest to the oldest, hear these words and learn these words until they become immune to them and used to using them..... The previous generations have already screamed on the danger of those who do their job in falsehood...."

the title page in the Renaissance Hebraica Facsimile of the book