Why The Spice Must Flow
The spice mélange.
A friend of mine recently asked for a description of the spice mélange as it is found in the Dune universe. The spice is considered to be a vital food/drug of the empire. Even though the original Dune was written in 1965, there is an obvious corollary to oil as the spice is only available on one planet and the production/harvesting of mélange holds a direct influence on the economy of the entire empire.
The spice is used by almost all of the populace in the empire for various things. As a food additive, it does add flavor and is actually a food source on its own. Habitants of Arrakis (Dune) have been known to survive on pure spice in times of need. However, its life-extending properties are what most other citizens of the universe use it for. In continual small doses, it extends a human’s life span to (I believe) just over 200 years.
However, this is not the main impact that the spice has on the economy. When taken in heavier doses, mélange will have a heightening effect on an individual’s awareness. Because of this effect, it has become integral to the dominant religious group called the Bene Gesserit. As the Bene Gesserit take the spice in heavier doses more regularly, the addictive nature of mélange grabs hold, and withdrawal is something all Bene Gesserit fear.
This heightened awareness is integral to another group's functioning, as well. And this is where the true economic influence comes into play. Guild Navigators pilot transports from star system to star system by “folding space”. Transports are massive ships large enough to contain and transport hundreds of space ships within its holds. They use an engine that is capable of folding the space-time continuum and touching two points thereby placing the transport in two locations at the same. This allows for near instantaneous movement across unlimited distances, and this is what is truly vital to the economy of the empire. Otherwise, it would take months/years to travel between even the closest of planets.
Guild Navigators literally immerse themselves in tanks filled with spice in a gaseous form to heighten their awareness to a point that will allow them to perform the calculations required to prevent the transports from reappearing in the middle of a planet or some other catastrophic misplacement.
The spice holds more relevance in the development of the epic that is the Dune series, but that is the general situation that a reader will encounter when starting the books.