In the book Gathering Blue by Lois Lowry, one simile that is contained in chapter one is when Kira tells Matt she has watched her mother's spirit leave her body. She says:

"My mother's spirit has gone," she acknowledged. "I watched it leave her body. It was like mist. It drifted away."

This simile compares the image of Kira's mother's spirit to a mist. It gives readers a visual idea of what a spirit looks like.

Another simile occurs on page 22 of the edition of the book I'm using. Here it is: "Her stick thumped on the wooden floor, and the foot of her flawed leg brushed the boards with a sweeping sound as if she dragged a broom." Here, the sound of Kira's foot is described as sounding like a broom. Again, it offers the reader a sensory explanation of what her foot sounded like as she walked.

An example of a metaphor from the book occurs on page 159 in the edition I'm working with. Kira and Thomas are traveling in the Fen, and Kira asks why it has to be so horrible. Thomas replies that it has always been that way, but Kira knows this isn't right because of her work with the robe.

A sudden vision slid into Kira's mind. The robe. The robe told how it has always been; and what Thomas had said was not true. There had been times—oh such long ago times—when people's lives had been golden and green.

The author compares their former lives with colors, without using like or as. What the metaphor means is that life used to be beautiful and fruitful. Green is the color of life, and something that is golden is valuable and cherished.

There are many possible themes in this novel. I will mention two here. One lesson readers could learn from reading this novel is to never give up no matter the odds. Kira has reasons for hopelessness, with both her parents gone and with her handicap. But she chooses to hang on to the words of her mother and to believe she has worth. Another possible theme for this novel could be that home is where you make it. Kira loves her mother dearly but has never known her father. She's only heard stories of him. When her mother dies, she has to make her own home and find her own family. When she finds her father at the end, she realizes that even though she wants to be with him, her home is elsewhere, and she must stay loyal to the home she has created for herself.

One simile that comes fairly early in the book is the following simile.

She nodded. "My mother's spirit has gone," she acknowledged. "I watched it leave her body. It was like mist. It drifted away."

Kira says that she watched her mom's spirit leave "like mist." It gives a good, specific image that allows readers to imagine what a departing spirit might look like. The very last line of chapter 1 contains a solid metaphor about Kira's emotional state.

It came as no surprise. Nonetheless, Kira's heart sank.

Obviously, her heart didn't actually sink. That would be a serious biological problem. However, the statement does convey her sadness.

Regarding themes, I think a prevalent theme is one of power and freedom. The Council of Guardians have huge amounts of power over the villagers. This power comes from their ability to psychologically manipulate the rest of the population. Another theme is art and creativity. The general thought about art is that it is useless because it doesn't serve any practical purpose, yet Kira, Thomas, and Jo all excel at one form of art or another.

The first metaphor I see in the book is on page 2.  It says that, as Kira watched her mother's spirit drift away, she could also see the "cindered fragments" of her childhood going up as well.  Obviously, her childhood had not been burned and made into fragments.  So this is a metaphor that is meant to show that her childhood is over.

Then, on page 27, we see Vandara say that Kira drags her leg around "like a useless burden."  That's a simile because it uses the word "like" to directly compare two things.

As for themes, there are many, but you can argue that the most important one is the theme of how important creativity is -- that is why the Council of Guardians takes all the creative kids and controls them.