"Als Gregor Samsa eines Morgens aus unruhigen Träumen erwachte, fand er sich in seinem Bett zu einem ungeheuren Ungeziefer verwandelt."
"When Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in his bed into a gigantic insect."
Perhaps Kafka's finest and most typifying sentence, this opening line of The Metamorphosis hits the reader like a blunt object. The first thing I'd like to note is the evocation of horror by means of the blase, the typically Kafkan mode of punctuation-by-banality. Samsa does not scream, and he is not afraid. He's barely confused. "A gigantic insect? Oh." Like Josef K. discovering the whipping men in the closet of his office, we are merely informed of what is, without any attempts at the elucidation of the reason. And it is the question we mean to ask right here, and don't, cannot, that haunts the reader throughout the remainder of the text. A question that we had expected to arise as a reflex does not come, and from here stems a sense of vertigo.
And there we've had it. That's the metamorphosis. The story climaxes in its very first sentence, establishing an uncanny and perhaps unprecedented sort of structure. The volume slowly fades with each page from here on. The entire shape of the novella is thrown off, is irregular, is mangled.
The mention of Samsa's having awoken from "uneasy dreams" appears at first to allude to a symptom of his overnight mutation, but it must also be understood as a flight from unreality. Samsa has awoken. The implication that Samsa has returned to the true is unavoidable. Perhaps the uneasy dreams from which he'd awoke were the dreams of his humanity. Perhaps he's come to confront his true form. Kafka explicitly states: "It was no dream." The uneasy dreams have subsided. This, Gregor Samsa, is what you have become.
Why an insect? Throughout the story we see Samsa painted as a fellow preoccupied with the practical side of life, a man leading a life of pure utility. In the frame in his room, which he would later throw his insect body against to protect from his family, was a cutout of a woman from a magazine. This frame, how it is situated, how Samsa reacts to it, ought to have been reserved for a picture of a girlfriend or a scene from his own life, but instead it is inhabited by fantasy, by what Samsa does not have, does not want, does not know to hunger for.
This theme is reinforced by just about everything we learn of Samsa over the course of the remainder of the text. His obsession with his sister's music is not a passion he can enjoy directly, but rather a passion he can only enjoy through his sister. In other words, his love of her musical endeavors is a love of the fulfillment of his own duty more than it is a personal passion. Samsa can only approach music through this harmless backdoor of his responsibility, that which must be done, rather than as a choice, as a will, as a desire.
We learn that Samsa's enslavement to his boss is on account of the debts of his parents. Samsa fantasizes about talking back to his boss, a fantasy his character would be unable to realize. He would continue to bear the burden of the debts of his parents indefinitely. Fulfilling his responsibilities. Boarding this train and that, this train and that, like clockwork. He does not get sick, he does not take days off. His sexuality and any hobbies and any interests, all inklings of all passions, seem to have left him. He is a busy man. He is busy living like an insect. Perhaps becoming an insect could teach him to live like a man.