The book Mice and Men is about two men that live together and how one is not really smart. You can take quotes out of this book and describe them in a literal term or you can zoom out and put them in terms with the characters.
One quote from the book is "the Salinas river drops in close to the hillside bank and runs deep and green." In literal terms you can take out the word green and know that it means, natural, the earth, fresh growing plants. Another phrase you could take from the qoute is runs deep means that it is solid or a deep river. Close is another word you could use and it could mean close like close the lid or close as when your close to somebody. These terms can be turned into a way so they transter to the characters like green means how Lenny is young in a way h0w he does not act like an adult usually. Runs deep can also means how George is more of a deep person and how his thoughts are more deep and complex than Lenny's.

Another quote from the book is " slopes curve up to the strong and rocky Gabilan mountains." The word strong means to have stength, just like a rock is strong, sturdy, and can be held on by its self. A way it can be used to explain Mice and Men is that Lenny is strong with his muscles, but does not really have a strong mind. George is like a rock in a way, he is the foundation two the pair of them he is also strength in his mind.
The last quote is " under the trees the leaves lie deep and so crisp." A tree is a large plant that comes in many different species, it also has roots that are the base of the tree. Leaves grow on the tree and fall off every year. George is the tree he has plans where the two them are going to live and is the mind between the two. Lenny is the leaves on the tree, George does not need Lenny to survive but Lenny needs George to survive. Just like leaves need a tree.
Tone
The tone of the book is desperation and bitterness to the place they are in life and how they do not really have a say in how their life unfolds. Candy is eager when he hears George and Lenny talking about the place they want to get and he wants to be a part of it to and George is on guard right from the start from telling him anyting.
Eager is the first word that sets teh tone "Candy said i got two hundred and fifty dollars cause i lost my hand and i have fifty more comin the at the end of the month. Tell you what he leaned forward eagerly. Suppose i went in with you guys and i could live there with you. These quotes show how eager Candy is to get out of this ranch and actually live on his own and not take orders from others anymore. It tells how eagers he is because he is willing to go into buisness with two strangers and give them three hundred and fifty dollars.
The other term is on guard "George sat in trance of his own picture. When Candy spoke...you know where' s there a lace like that? George was on guard immediately.S'pose i do he said whats that to you?....I gotta think about that. We was always gonna do it by ourselves" George is on guard about telling anybody about his plan to get his own place he does not want to have is hopes up and someone to cursh his dreams. George is defensive because he feels he cannot trust anybody.
These to words help the tone of the book change from Candys point of view on how he is eager to start a new life. Than George who is guarded because he cant trust anybody.
This is how the tone works on a novel how the other wants you to see how the characters feel.

Being your brothers keeper is sometimes a burden that we have to bear. In the novel Mice and Men George is Lennys keeper. He makes sure Lenny stays out of trouble and when he cant keep him out of it he runs off with him and finds a new job. He also helps Lenny dream he gives Lenny hope of a better life were he will "take care of the rabbits". George also had to a hard thing which was take Lennys life for his own good. Sometimes being a persons keeper is not the best thing in the world but its something we all have to do.

I believe in the statement being my brothers keeper. For one i have a younger brother who does have some certain dissablities and i know i will always be there to protect him if he needs me. I believe it is one of the reasons God put us here was to look out for each other. We all need somebody to lean on because mankind is not perfect and we all need help sometimes. So i belive that we are all are brothers keeper.