The Issues
The Dune Empire as compared to the Roman Empire
In a common theme in science fiction novels describing empire, Herbert paints a picture of an empire in decline, overrun by its own gluttony and decadence. Lorenzo DiTommaso shows that these excesses are shown throughout the novel as an indication that the empire is coming to an end. The Fremen, by contrast, are stalwart, spartan and lacking in luxury. While the empire abuses spice as a luxury and become heavily addicted to it, the Fremen use it as a food source. This point is an important one because in Herbert's previous novel, The Dragon in the Sea, two major powers fight over limited supplies of another, more familiar resource: oil.
Dune's Unique and Complex Ecosystem
While water is important to any human life, Arrakis faces an interesting problem. The planet is very dry, and although it could potentially be turned into a more lush planet, the Fremen must respect the sandworms which die in contact with water. The sandworms are crucial to the Fremen way of life, as they are the producers of spice. This creates interesting and complex ecological issues, something not seen in science fiction novels before. Instead of focusing merely on technology, Dune also brings into focus ecological issues.
The Hero Myth
The protagonist's journey has many of the characteristics set up by Joseph Cambell in his book The Hero with a Thousand Faces, following a now stereotypical hero's journey. Although he starts off with some power, he is nothing compared to what he is to become. He is raised, then faces a series of trials. As he faces these trials and gains in power, he finally faces an ultimate trial - in his ingestion of the "water of life" - and almost dies. He survives, as in any good hero tale, and his apotheosis is complete: he has become almost godlike in nature, dwarfing all other humans in terms of power, as he can see the past, present, and future.
Foresight and Inevitability
The idea that Paul and others can see into the future raises interesting questions about human will, freedom of choice and the futility of actions. DiTommaso thinks that these tie into the religious motifs, in that the religious prophesies, even though they come about in a completely different way than anyone had intended, were inevitable.
"The development of Paul’s prescience forces the novel along a series of decision/nexus points. Paramount among these critical junctures is the seismic movement throughout the book to the coming jihad, which certainly ties in with the much-discussed Vitality struggle. Indeed, throughout the central part of Dune, Paul almost bends over backward trying to avoid the coming holy war. "
-Lorenzo DiTommaso