There is a great deal of symbolism in Kafka's The Metamorphosis. One example is the question of whether Gregor's transformation is symbolic of his sense of alienation? Is he a bug or is he simply feeling alienated from all those around him in that he is not appreciated?
The first line of the story begs the question of whether the story is a dream:
As Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in hi bed into a gigantic insect.
There is supposed to be a great deal of symbolism in dreams, so Kafka may be suggesting, by introducing the possible presence of a dream, that this might simply be a…nightmare. Gregor works very hard and it is no surprise that he might worry in his sleep about the job that is so important to his family. The vision of turning into an insect could actually symbolize his desire not to have to return to a job he hates.
One of the themes of the story is alienation and self-sacrifice. With this is mind, it has been argued that Gregor is a Christ-like figure. We see symbolic references in several events.
Grete, Gregor's sister, was once very close to him, but by the story's end, she is demanding that they get rid of him because he has changed. This is similar to Judas' displeasure, politically, with what Jesus was doing.
When Mr. Samsa throws the apples at Gregor, this might be symbolic of the abuse and heckling Christ receives on his way to Golgotha—because although Christ was welcomed on "Psalm Sunday," many people were disappointed with the man he was as opposed to the warrior king they expected. (Gregor is perceived as valuable when working, but not when he changes and cannot work.) With the apple that lands itself in his back, Kafka writes:
One weakly thrown apple grazed Gregor's back but slid off harmlessly. One direct hit that flew immediately afterward penetrated Gregor's back; Gregor wanted to drag himself a little further, as if the unexpected and unbelievable pain would go away with a change of position, and yet he felt like he was nailed down and stretched out...
This gives a description similar to the nailing of Christ to the cross: feeling "nailed down and stretched out."
(This symbolic allusion continues: even after the way his family treats him, Gregor's reaction is also Christ-like:
He thought of his family with tenderness and love.
Ironically, the family (except for his mother) may never have really loved him as much as the money he made—which he cannot do as a bug. There is also Gregor's death, where the time, three o'clock is significant, as it is in the crucifixion story:
In this state of vacant and peaceful meditation he remained until the tower clock struck three in the morning…Then his head sank to the floor of its own accord and from his nostrils came the last faint flicked of his breath.
It is said that Christ died at three o'clock in the afternoon. The three lodgers might be symbolic of the Jewish high priests and elders of the Sanhedrin; the lodgers were "serious men, all three with full beards." (Three is also a number highly symbolic in the story of Christ: rose on the third day, died in the third hour, the trinity, Peter's denial three times, etc.)
Finally, the charwoman enters Gregor's room that morning. With a broom handle in her hand, she pokes Gregor in the side to waken him, and finally realizes that he is dead. This might be said to be symbolic of the centurion's spear, used to pierce Christ's side to see if he was dead.)