He turned, and upon his face was a mask, hammered from silver metal, expressionless, the mask that he always wore when he wished to hide his feelings... ("Ylla," 160)
Oh, hi there, theme of identity: the book starts with a character literally putting on a mask in order to hide his feelings and plans. Got it.
"This is the planet Tyrr," she said, "if you want to use the proper name." ("The Earth Men," 13)
The Earth Men of the First Expedition think they're brave explorers, while everyone else thinks they're crazy Martians. So, who's right? Who gets to name something? If we're just basing our answer on this story, it looks like only the individual gets to name himself. But what about when it comes to naming Mars?
"I christen thee, I christen thee, I christen thee—" said Biggs thickly. "I christen thee Biggs, Biggs, Biggs Canal—" ("—And the Moon Be Still as Bright," 57)
Spender is super worried that people will come to Mars and give everything new names because they don't understand the old ones. And, gee, it looks like he's right. Here, the idiot Biggs tries to rename a small portion of Mars after himself.
"And somehow the mountains will never sound right to us; we'll give them new names, but the old names are there, somewhere in time, and the mountains were shaped and seen under those names." ("—And the Moon Be Still as Bright," 75)
Since The Martian Chronicles involves a lot of exploration, there's a lot of naming of places that already have names. For Spender, the fact that Mars had names means that there's some identity there that we can't change. In some way, the land remembers its identity. Does that make any sense, or is Spender just crazy? (Or… both?)
"I'm the last Martian," said the man, taking out a gun. ("—And the Moon Be Still as Bright," 127)
We don't yet know that this man is Spender, which is an interesting delaying tactic on Bradbury's part. Why does Spender identify himself this way? Is he right? Do you have to have brown skin and "yellow coin eyes" to be a Martian—or is being a Martian more about the way you feel?
"No," said the captain. "There's too much Earth blood in me. I'll have to keep after you." ("—And the Moon Be Still as Bright," 269)
Here's something that might explain why so many characters go back to Earth after "The Watchers." Wilder thinks he's got too much "Earth blood" to go native like Spender—and it seems like there's something innate that makes people long for home. We have to wonder if humanity could ever be happy somewhere other than on Earth.
"But what is a shape? Only a cup for the blazing soul that God provides us all." ("The Fire Balloons," 178)
This is a religious argument in a book without a lot of explicit religion. The book gives us lots of examples of Martians changing their shape, so the question is whether changing one's appearance affects one's identity? Or is there something deeper than appearance that remains the same? (Bonus points if you can use this to figure out why the Martians in "The Third Expedition" hold an Earth-style funeral.)
"I'm not anyone, I'm just myself; wherever I am, I am something... " ("The Martian," 155)
Ooookay. This is the Martian who looks like Tom talking to LaFarge, and it's a bit brain-melty. Does the Martian really have no identity? And if this Martian isn't anyone, then who is "myself"? Is it possible that Martians actually have no core identity?
The swift figure meaning everything to them, all identities, all persons, all names. How many different names had been uttered in the last five minutes? How many different faces shaped over Tom's face, all wrong? ("The Martian," 188)
This statement is from LaFarge's point of view, as you can see by (1) the fact that the quote ends with the idea that his is the base face ("different faces shaped over Tom's face") and (2) the idea that all those other faces are "wrong." Maybe we should think it's sad that LaFarge wants to restrict "Tom's" identity to just one person.
The Martians were there—in the canal—reflected in the water. Timothy and Michael and Robert and Mom and Dad. ("The Million-Year Picnic," 138)
Pretty cool way to end the book, huh? Is this family now a Martian family? Dad burned all their old Earth papers after all. The book opens with the image of snow melting to reveal the older identity of summer (the grass is "ancient" ["Rocket Summer," 2]), and it ends with the idea of a new identity replacing an old one. So... can identity change, after all? Will this family end up with Martian blood rather than Earth blood?