Joseph’s ability to resist the allure of Potiphar’s wife led the rabbis to crown him “Joseph the righteous”. But how righteous was he? Rashi explains that Potiphar’s wife’s attempt to seduce him happened on a pagan holiday; Potiphar’s family had gone out to celebrate, but Mrs Potiphar feigned illness, so she was alone in the house when Joseph arrived “to do his work”.

What work had Joseph come to do? The rabbis were divided. Some took the words literally: like any other workday, Joseph had come to administer the household chores. Others argued that the word “work” is euphemistic, suggesting that when Joseph arrived at the empty house that morning, he had other business in mind. He was preparing to commit adultery, but at the last minute he resisted. What stopped him?

The Talmud suggests that although “none of the household was home that day”, another presence was. Just as he was about to sin, Joseph saw his father’s image cautioning him to resist temptation.

What did he see? Perhaps it was a prophetic vision or hallucination. The Israeli writer Rabbi Chaim Sabato offers another ingenious solution. In an age when mirrors were scarce and luxury items, Potiphar’s home would have been one of the few to have one. Joseph’s face bore a striking resemblance to his father’s, so when he caught a rare glimpse of his own reflection in the mirror, he saw his father’s face gazing back. This was enough to prick his conscience and prevent him from sinning. It took greatness to see his father at that moment and to hear his message. Joseph was indeed a righteous man.