The path of Gaia is better known as the path of the Garou in second edition Werewolf: The Apocalypse.
The path of the Garou was described as the Garou's version of humanity because they had never been human but it also included features of the Path of the Feral Heart. The path of the Garou also represented a closeness to nature and to ones instinct. Can be seen as roughly equivalent to the path of harmony. Before this the 1st edition presented the same path as the path of ego which also represented the Garou's "natural path" since they never been human. The path of ego focused more on the Garou's gnosis and his sense of self, identity and inner harmony. In Vampire: The Masquerade revised it was settled that the Garou's gnosis rating was their natural code. All these paths had basically the same hierarchy of sin based on Wyrm taint but the outlook of what the rating meant differed.
In the Outcast splatbook the same path is re-presented as an hierarchy of Wyrm taint only without any real path. It was only a rating of Wyrm taint or increasing inner sickness but not of any moral quality that was deteriorated. This taint system was for Ronin Garou who had no sense of honor or renown which was the thinking system of the Garou. Compare this system to torment in Demon: The Fallen.