"Didactic" is a fancy way of saying "instructive." The Chosen doesn’t just tell us a story. It also teaches us about different aspects of Judaism and history. And this is reflected in the novel’s style.
At times the didacticism seems like mildly irritating – remember when Reuven tells us over, and over, about how he’s nauseous, dizzy, and his eye hurts when he’s on his way to the eye ward? But that’s just Reuven warming us up to understand more complicated things, like Talmudic passages, which, as we now know, are made up "of thought units." We also know that every "thought unit is a separate stage of the total discussion that makes up the passage." Reuven is a good teacher, though, and he doesn’t just drop a bomb like that on us and move on. He takes us through the process of understanding it. As the novel grows along with its characters, we find that Reuven’s repetition of basic ideas is not without a point. Eyes, Talmud, silence, Torah, friendship, Zionism – to name a few of the repetitions – come together in a delicate, painful, and exuberant rhythm as we gain intimacy with Reuven’s world, and as he becomes more comfortable telling the story.
OK, quick question: Which classes to you like better – the ones where the teacher lectures for an hour or the ones where the teacher is constantly asking the class questions, and loves nothing more than to get a rollicking debate going? As long as you’ve done your homework, so you know what everybody’s talking about – you probably prefer the second type of class. And that’s a major aspect of The Chosen’s didactic style. There are questions on every page. The characters never stop asking questions and trying to get at the deeper meanings of things. Many of these questions are so universal they apply to our own lives. By the end of the novel, we know that the main point the novel wants to teach us is to never stop asking (and trying to answer) the hard questions about our lives.