The quote "A fly will never be able to enter a mouth which knows when to stay shut" from Jean Sasson's "Princess Sultana's Daughters" emphasizes the importance of discretion and self-control. It suggests that knowing when to refrain from speaking can protect one from unnecessary troubles and distractions, akin to how a fly cannot land on a closed mouth. This metaphor highlights the value of patience and careful consideration in one's words and actions.

Additionally, the quote reflects a broader theme in Sasson's work related to empowerment, particularly for women. By advocating for the wisdom of silence, the author encourages individuals, especially women, to recognize their power in choosing when to engage in conversation or assert themselves. This choice can lead to greater control over one's life and circumstances, serving as a reminder of the strength that comes from self-awareness and restraint.