! Who Are You? What Do You Want?
The core of the story is a great war between two vastly-different ideologies, the forces of order and chaos. The Vorlons represent the forces of order and believe that growth comes through organisation, discipline, cooperation, self-sacrifice, etc. They believe their role is to act as stewards and shepherds for the younger races, guiding them towards a more enlightened state by subtle interference in their natural development. Their philosophy is embodied in their question, "Who are you?", which is about somebody's relationship to other people and the universe at large.
The Shadows, on the other hand, are the embodiment of chaos. Their core belief is in the power of evolution, and that evolution is best served by disorder and conflict. By triggering wars, they think that the protagonists in those wars will be forced to make faster scientific progress then they otherwise would have, and that the winners in those wars are genetically superior to the slain and are therefore more likely to evolve and are more deserving of survival. Thus, war and conflict serves as a force to prune the undeserving away, leaving the strong behind to thrive in the aftermath. The analogy they use is that of the ant-hill. If you destroy one, then the ants would build a replacement that is superior to the destroyed ant hill. They therefore choose to execute a cycle wherein they hide away for a considerable period of time, quietly manipulating other races by stirring up conflict between them and then emerge in force to metaphorically kick over all the ant hills. Their question, "What do you want?" encourages those asked to think in selfish terms and put their own needs before those of the groups to which they have a duty.
These points of view are initially set up in the series as those of the good guys and the bad guys, but as the story progresses it becomes clear that things are a lot more complicated than that. While order is portrayed as good and chaos is portrayed as bad, it is not always the case. Order, in the form of a dictatorship for example, can be a force for great evil, and chaos can be a force for good in the right circumstances. Our heroes certainly rely on luck on more than one occasion, and luck can be considered random and chaotic. Meanwhile, the Earth government (ironically under the influence of the chaotic Shadows) try to impose a new order that is authoritarian, oppressive and unjust. The biggest issue is that both sides, the Vorlons and the Shadows, have been so wrapped up in the philosophical debate between their points of view that they are now failing in their role as mentors to the younger races. They would rather wipe out each other's disciples in a pointless all-encompassing war to try and prove to the other side that their position is the right one.
In the end, the Vorlons know who they are, but not what they want, and the Shadows know what they want but don't know who they are. In order to really be in a position to mentor the new races, you must be able to answer both questions. A truly fair galaxy should embrace both order and chaos and not fear either.