"Conservation" by Charles L. Fontenay is a science fiction novella written in the mid-20th century. The narrative explores themes of technological regression and human survival in a post-apocalyptic Earth, where vast advancements in power and technology are present but largely unutilized. The story is set after a period of catastrophic warfare, presenting a society that has adopted stringent conservation measures to guard against potential threats while neglecting to fully harness their technological capabilities. The plot follows a crew led by Executive Officer John Gray as they return to Earth after a 258-year absence due to their mission to colonize a planet elsewhere in the galaxy. Upon landing, they encounter a military society that lives amidst advanced machinery yet chooses to use a rudimentary lifestyle reminiscent of earlier centuries. The crew grapples with local customs, governance, and a poorly understood legal system focused on conservation. As they uncover the motivations behind the society's apparent technological hostility, they learn that the Earth has been occupied and had a long struggle against alien invaders. Ultimately, their knowledge and skills from the Deneb III colony may offer a path to rebuilding Earth’s lost technological prowess and help restore a more sustainable future. (This is an automatically generated summary.)