Repetition

Returning to the same word, the same phrase, or the same construction, at the start of verses or of successive sentences (anaphora) or throughout the text, to give rhythm, emphasis, or insistence.

In The Idiot

but the main pain, the strongest, perhaps is not in the wounds, but in this: knowing for certain that in an hour, then in ten minutes, then in half a minute, then now, right now, the soul will fly out of the body, and that you will no longer be a man, and that this is certain; the main thing is that it is certain.

The word “certain” returns at the end, “that this is certain; the main thing is that it is certain.” The repetition drives home the central idea, that what hurts most is the certainty, and the sentence ends by striking that point.

Part One: The Arrival, Myshkin

everyone also takes me for an idiot, I don't know why; in fact, I was once so ill that at that time I seemed like an idiot; but what kind of idiot am I now, if I myself understand that they take me for one? I go in and think: here they take me for an idiot, and yet I am intelligent, and they don't suspect a thing...

Part One: The Arrival, Myshkin

didn't I dream about you myself? You are right about that, I dreamed of it long ago, still in his village; I lived alone for five years. One thinks and thinks, dreams and dreams, and it is always someone like you, good, honest, kind, and just as simple, who suddenly arrives and says: you are not to blame, Nastasya Filippovna, and I adore you!

Part One: The Arrival, Nastasya

That day we felt the same thing, in one word. If you had not raised your hand against me (the hand God turned aside), what would I be now before you? For I suspected you of it too, one sin, ours, in one word!

Part Three: The Explanation, Myshkin

And let us finally dare to say that the springs of life have not weakened, have not been clouded under this star, under this net that has ensnared men. [...] There is more wealth, but less strength; the idea that united us is gone; everything has gone soft, everything has rotted, and everyone has rotted! All, all, all of us have rotted!

Part Three: The Explanation, Lebedev

the prince then reached out to him with a trembling hand and lightly touched his head, his hair, smoothing them, and smoothed his cheeks... he could do nothing more!

Part Four: The Denouement, the narrator