2. Several subtle threads tie all of the chapters and time periods together. Describe two of these, such as the "comet-shaped" birthmark, and give examples from each pair of chapters.

In Chapter One, the last letter of the chapter finds Frobisher lamenting ever getting involved with Jocasta. In passing, he mentions a birthmark the shape of a comet in the hollow of his shoulder, a connection to the previous chapter.

In Chapter Five, an "Orison of Sonmi-451" carries hints from the previous chapters. Chief among these is Sonmi's birthmark, a red comet-shaped mark between her shoulder blade and breastbone, similar to those that Frobisher and Luisa Rey have discussed. It's interesting that a fabricant should have such a mark, since clones are made, rather than born of man, but this point is never explained. There is also the obvious tie to the "Timothy Cavendish" story. The movie that has been made of Cavendish's tale is the movie that Sonmi and Hae-Joo are watching when they learn of the Professor's capture and their peril.

In Chapter Six, the comet-shaped birthmark, which Frobisher, Luisa Rey, Sonmi, and Timothy Cavendish all mention, reoccurs in "Sloosh'a's Crossin'." Meronym, too, is marked with the distinctive birthmark, hinting that all of the characters are reincarnations of each other.

In Chapter Eight, the reader learns that Cavendish has the tell-tale comet-shaped birthmark, just like Luisa Rey, Frobisher, and Meronym.

The continuity and rebirth of life is a repeating theme throughout Cloud Atlas. All of the main characters - Adam Ewing, Robert Frobisher, Luisa Rey, Timothy Cavendish, Sonmi-451, and Zachry - have a comet-shaped birthmark between the shoulder blade and their collarbone. In addition, there are subtle references to reincarnation, such as Luisa's being familiar with Frobisher's "Cloud Atlas" concerto, even though it is highly unlikely that she has ever heard it before