Shivan Manifesto
This article is about an individual fan's or a group of fans' interpretation of canonical information, and should not be considered as part of the official Freespace continuity
Summary of the Manifesto
The Shivan Manifesto was a long and extensive document written (and later revised), on the origins and motivations of the Shivans. Essentially, the theory is based on the idea that the Shivans are energy beings from subspace, that use a kind of exoskeleton to maintain integrity in our own plane of existence. Also central to the theory is that the subspace travel performed by Terrans and Vasudans is harmful to subspace, and as a result, causes the Shivans to aggressively defend their home dimension whenever large levels of subspace activity occur in any given area of space.
The theory also explains the Shivans' motivation for destroying Capella as an act of fear, lest the GTVA deploy more Colossi in large numbers, as they were not able to understand how a civillization's technology could evolve so quickly. It also suggests that this retreat is due to the SOC mission where you are ordered to destroy a number of unknown Shivan devices, which the Manifesto states are responsible for Shivan life-support.
Support for the Theory
The theory itself is based largely on conjecture from both the Ancients and Bosch monologues in Freespace 1, and Freespace 2, respectively, and a number of the ideas (such as the Shivans as energy beings) are not mentioned by any canon sources. As a result, the theory itself is highly controversial among Freespace fans (and is certainly not generally accepted as an official interpretation of events).
Text of the Manifesto
The full text of the Manifesto can be found in PDF Form