The dead parents
The hero without parents is a motif that has symbolic implications. First of all, this means we are dealing with a melancholic, reflective, observant character, because he has had the full experience of life's pain and sorrow thrust upon him at a young age. Lewis's story is to make meaning from his suffering by accomplishing his destiny, and his magic qualities come from his sincere knowledge of deep existential pain.
Magic through motif
The novel shows what magic is through the use of motif. There are good witches and bad witches. By the end of the motif, we see that the ultimate use of evil magic is to accomplish one's resurrection from the dead to immortal life through evil means, typically through murder. In light of this dark prospect, the use of good magic could be seen as the opposite—to use magic well is to help one another to deal with the tragedy of life as it is designed.
The mysterious ticking noise
Lewis is puzzled by the mysterious ticking noise he hears through the house. This is a sign of his paranoia, because it is disturbing to him, and it is a sign of time, because he uses clocks to deafen the noise, and the ticking is a constant reminder of the threat of time, a threat that he knows all too well because his parents have died; he knows what time means. It means the ultimate end of everything, and because he knows this, he can't be comfortable with the constant noise. The noise is a symbol that death is always on his mind.
Selenna as a symbol
Symbolically, Selenna is an anti-Christ, because Jesus is the symbol most commonly associated with necromancy and rising from the dead, but Selenna has accomplished the same goal without being good. In fact she has become evil to maintain her own immortality. She is an occult symbol of evil and the ultimate evil, to prize one's life so far above another that one becomes willing to kill. Selenna escapes her tomb through evil, so she is an anti-hero.
The lunar eclipse
The realm of nature is a common source of meaning in stories like this, especially the moon. Lewis's ability to do magic with the moon is seen when he is trying to impress Tardy, but Tardy doesn't see the merit of his magic. The magic is that Lewis understands the cycles of time, and that he has mastery over a feminine, lunar aspect of his self, perhaps through suffering. Tardy doesn't understand this, so they are complementary heroes, because they have different strengths.
