The Color Red
OK, so what do you think of when you think of red? Fire, passion, and love…exactly. Red is a pretty intense color. Possibly the intense color. So when Jonas starts seeing the color red, he's not just seeing the color red. He's seeing passion, fire, and love. That's why it's so fitting that Fiona – the girl Jonas does have feelings of attraction for – has red hair. It's also fitting that at the peak of the novel's emotional intensity – when Jonas is trying to survive and clinging onto desperately to his last bit of hope and courage – we get the color red again, this time in the sled he finds at the top of the snow-covered hill. See how that works out?
Because Gabriel is a baby and can't talk or emote in any discernible way, he's really more of a symbol than a full-fledged character. So what does Gabriel symbolize? Well, to Jonas, Gabriel is a pal. Jonas identifies with him. There's that whole light eyes thing (and we have more to say on that in a bit) and the fact that they can share memories together. But why does Jonas choose Gabriel to share the memories with? Because he's a baby, and because he's in danger of soon being released, Gabriel in many ways exists outside the rigid control of the community. Jonas can't transmit memories to Lily because she's too ingrained in the "people shouldn't touch other people" mantra of the community. Gabriel, however, is untainted; he's pure and free.
All the more reason to try and protect him. Because Gabriel hasn't yet come under the thumb of the community's control, he's also a symbol for a brighter future. When Jonas escapes with Gabriel (maybe, unless they die), we get the sense that there is hope for us all.
There's also something to be said about Gabriel's name, but for that you're going to have to check out "Tools of Characterization." See you there.
The sled first comes up when The Giver compares the process of receiving the memories to sliding downhill in the snow. At first it's all birthday parties and wind in your face but, before you know it, your arm's being blown to pieces (which, in his comparison, is like snow piling up on your runners. Right…). Jonas then gets to experience this himself, as the sled is his first memory. Of course, we see the same sled again at the end of the novel, as Jonas races downhill toward the village that's either a hallucination or the Elsewhere of his dreams.
Because The Giver explicitly spells out the simile for you, there's not much more to say in the vein of "riding downhill = receiving memories." But we can think about what it means when Jonas actually does ride down the hill at the end of the novel. Until now, this action has been a sort of dream, someone else's memory, someone else's exhilaration, someone else's difficulty and pain. But now all of these things are very much Jonas's own. The novel even states explicitly that now Jonas is using his own recollections, rather than drawing on the fleeting memories passed on to him by The Giver. In short, his dreams have become reality, and the sled clues us into that. Of course, it's also possible that the final sled ride is just Jonas's memory, and that it's not happening at all, which would really shoot that theory down.
There is definitely an association in The Giver between those who can receive memories and those who have light eyes. There isn't really any explanation for why this is, and it would pretty useless for us to sit around and speculate about why this is, logically or scientifically. It's better to think about it as an artistic device that Lowry used to help us make certain connections. For one, Jonas's role as The Receiver is in some way pre-destined. He was just born with the right attributes to be The Receiver. It fits. He's supposed to do this. Light eyes also clue us in to the fact that Jonas and The Giver share a special bond, something that others, try as they might, will never have. Likewise, eyes signal the close bond that will form between Jonas and Gabriel; we suspect something is up even before Jonas transfers memories to the little tyke
But why eyes? And why light eyes? Jonas himself says that he always thought there was something peculiar about this feature, that it somehow signified "depth." Indeed, Jonas has a way of seeing deeper than others. The way he perceives the world is different – more reflective, more contemplative, more insightful – so it makes sense that his eyes appear different than everyone else's.
There's a lot you could say about the river and symbolism, and none of it is necessarily right or wrong. You could go with the "you can't step in the same river twice" argument, which is to say that the river symbolizes change, an important idea in Jonas's static community. Or, you could say that river symbolizes the boundary between Jonas and the rest of the world. On the other hand, rivers flow, right? So it could be about the river flowing out, away from Jonas's community, in the direction he will eventually take himself. Then again, there's a lot of death associated with the river – first with the child Caleb and later as the site of Jonas's planned fake death. Jonas first thinks of release as escape from the community, and later learns that release is really death, so the river is, in a way, both about leaving the community and about dying. Funny, because that's what the ending of The Giver is about, too.