When Amir reminds a fellow gardener that she once called him a "dirty foreigner," she replies, "Back then, I didn't know it was you..." What does...

In the book, Amir tells of the time an old Italian woman had complained about receiving the wrong change at his store. Because of her prejudice against foreigners, the woman likely believed that Amir meant to cheat her. This is why she called him a "dirty foreigner."

The old Italian woman later meets Amir at the community harvest festival, but it is obvious that she does not remember him from before. During the festival, everyone...

In the book, Amir tells of the time an old Italian woman had complained about receiving the wrong change at his store. Because of her prejudice against foreigners, the woman likely believed that Amir meant to cheat her. This is why she called him a "dirty foreigner."

The old Italian woman later meets Amir at the community harvest festival, but it is obvious that she does not remember him from before. During the festival, everyone trades vegetables and enjoys wonderful conversations about the harvests. The woman even confesses to Amir that she has admired his eggplants from afar for weeks, and she tells him how happy she is to finally get a chance to meet him. They discuss eggplants and the different ways to cook them; when the old Italian woman asks about Amir's family, Amir realizes that there is something bothering him.

Soon, he remembers what it is, and he tells the woman what's on his mind. The woman is visibly embarrassed and apologizes profusely. She tells him that "Back then, I didn't know it was you." This means that, previously, the old woman had let her preconceived notions about Indians cloud her judgment about Amir's character. Essentially, she misjudged him because of her prejudice. Her current statement alludes to the fact that, at the time, Amir was just another nondescript, untrustworthy foreigner to her. Now that the community garden has humanized Amir in her eyes, she regrets her past faulty judgment about him.