I forget a'the things. Tell about how it´s gonna be.
I ought to have shot that dog myself.
I done a bad thing. I done another bad thing.
George is talking to Lennie about their future, he is reluctant because he secretly knows that their dream is not going to happen. Meanwhile in the book there is a snake, the snake symbolizes evil. The snake symbolizes the evil that will come later in the book. Thus foreshadows later events in the book. The theme of this chapter is don´t have high expectations when it comes to making big dreams, reason being is that they may not come true.
Tell how it´s gonna be
Look acrost the river, Lennie an' I´ll tell you so you can almost see it
Candy is regretting not shooting his own dog, he loves that dog and feels useless without him. He is useless without his dog. In fact Lennie is much like the dog, both are useless without their protectors and the both end up getting shot in the same place. The dog getting shot also symbolizes the future events that take place in this book. The theme for this chapter is don´t let other people solve your problems.
Lennie killed Curleyś wife and now has to run away to the setting that was in the beginning of the book, the forest. Suddenly Lennie made a vast change from accidentally killing mice and puppies to killing people. Thereby leading up to the next events of the ´´evil" being stopped. Thus the theme of this chapter is you can´t run away from your problems.
George is killing Lennie like the heron is killing the snake symbolizing good killing evil. Before George killed Lennie there was a heron eating a snake foreshadowing the destroying of evil. Much like Candyś dog getting shot Lennie was shot too, only George did it himself. Therefore the theme of this chapter is you have to take matters into your own hands.