Slave as simile for humility
In Letter 2, Usbek writes to his First Black Eunuch (or Chief Black Eunuch, depending on the translation). Usbek is putting him in charge of the seraglio, so that he may protect and govern Usbek's wives in Usbek's absence. Usbek wants the addressee to be very much in charge, yet to maintain an attitude of humility. Usbek therefore instructs him to "serve them (Usbek's wives) like the slave of their slaves", meaning with great deference.
In the context of the rest of Letter 2, this request is extremely ironic: not only does Usbek want deference and command at the same time, the addressee really is a slave in a very literal sense.
Seraglio as empire
In Letter 9, the Chief Eunuch writes to his friend Ibbi, saying that he found himself in "the seraglio like a small empire" complete with various power struggles, command structures, and intrigues. This simile foreshadows the rebellion later in the book, when the women rebel against Usbek's absentee rule. Indeed, the rebellion of the seraglio parallels the ongoing collapse of the contemporary Persian government and possibly the French aristocracy as well.
Eunuch as a barrier
In Letter 9, the Chief Eunuch describes how he relates to the women of the seraglio. He "present(s) (him)self to them like a barrier" against their own desires, restricting and limiting their activities so as to deliberately fruatrate them. To the Chief Eunuch this seems like a sound management strategy that enhances his status. In reality it encourages rebellion.
Fatherhood as simile for love
In Letter 15, the Chief Eunuch writes to Jaron, another eunuch, saying: "and I would say to you that I love you like a father loves his son", except of course the letter writer is not capable of fathering a son. He means to say that he loves Jaron, takes pride in him, and worries about him during his long absence.
Husband as enemy
In letter 26, Usbek reminisces about how Roxana, after avoiding consummating her marriage to Usbek for two months, regarded him "like an enemy who had committed an outrage" when he finally succeeded in forcing her to have sex. Blindly, Usbek does not realize that his description of Roxana's attitude toward him was completely accurate. He believes she actually loves him. In reality, she hates him passionately and seeks revenge.
