LitCharts assigns a color and icon to each theme in The Sun is Also a Star, which you can use to track the themes throughout the work.
Immigration and the American Dream
Passion vs. Reason
Interconnectedness and Destiny
Isolation vs. Connection
Summary
Analysis
The narrator explains that according to scientist Carl Sagan, if a person wants to make an apple pie "from scratch," one must invent the entire universe. From a state of nothingness, or "from scratch," one must invent the Big Bang, the planet Earth, fire, agriculture, and cows. To make the pie good, one must invent the arts, and to make sure that the recipe can survive generations, one needs the printing press and the Industrial Revolution.
For most people, creating a pie “from scratch” means creating it from separate ingredients. However, Sagan points out that creating something “from scratch” means creating it from nothingness. To truly create a pie from scratch, then, one must first invent the universe and all of the conditions that make the ingredients able to exist, and then the person can make the pie from said ingredients. At the core of Sagan’s claim is the idea that everything in the world is interconnected—that’s why people can thank something as seemingly unrelated as a printing press for pie’s existence. Notably, this introduction also makes the case that the arts and the sciences are both important for humankind’s survival.