--- title: "Meaning & Key Takeaway of: In mechanical terms, humans are quite…" description: "\"“In mechanical terms, humans are quite efficient converters of food into energy, so human slaves were often more valuable than animal slaves, if one co..." image: "https://sms4smile.com/quotes/i/d28/david-christian-7861_fossil-fuel_in-mechanical-terms-humans-are-quite-eff_1602728.jpg" --- # In mechanical terms, humans are quite efficient converters… ![“In mechanical terms, humans are quite efficient converters of food into energy, so human slaves were often more valuable than animal slaves, if one could afford them.21 The importance of human beings as a source of energy helps explain why forced labor was so ubiquitous in the premodern world…” quote by David Christian](https://sms4smile.com/quotes/i/d28/david-christian-7861_fossil-fuel_in-mechanical-terms-humans-are-quite-eff_1602728.jpg) [Download](https://sms4smile.com/quotes/i/d28/david-christian-7861_fossil-fuel_in-mechanical-terms-humans-are-quite-eff_1602728.jpg) [Open image](https://sms4smile.com/quotes/i/d28/david-christian-7861_fossil-fuel_in-mechanical-terms-humans-are-quite-eff_1602728.jpg) > ““In mechanical terms, humans are quite efficient converters of food into energy, so human slaves were often more valuable than animal slaves, if one could afford them.21 The importance of human beings as a source of energy helps explain why forced labor was so ubiquitous in the premodern world, just as the existence of fossil fuels helps explain why human slavery has largely vanished today.”” [David Christian](https://sms4smile.com/quotes/author/david-christian/) ## About This Quote This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation. Human labor was historically valued for its energy output, making people more valuable than animals when affordable; modern energy sources reduced this reliance. **In simple terms:** People were once seen as energy sources, now fossil fuels replace them. Key Takeaway Recognize how energy economics shape labor systems. Themes history economics labor technology ethics Mood analytical reflective Type historical economic When to use this quote - pre‑modern agriculture - industrialization - modern energy policy - human rights debates Key Concepts energy conversion human value technological change Questions to Reflect On - How does energy availability influence labor practices? - What modern resources could reshape labor value? A Different Perspective The view oversimplifies complex social, cultural, and political factors beyond energy efficiency. ★ ★ ★ ★ ★ No ratings yet [Fossil fuel](https://sms4smile.com/quotes/about/fossil-fuel/) [Life](https://sms4smile.com/quotes/about/life/) [Slavery](https://sms4smile.com/quotes/about/slavery/) ## Related quotes > [“Both animal and human slaves could be controlled best if kept economically and psychically dependent on their owners.”](https://sms4smile.com/quotes/david-christian/both-animal-and-human-slaves-could-be-controlled-best-if-kept/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [The most racist, nastiest act by America, after human slavery, was the bombing of Nagasaki. 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He said that so many people…](https://sms4smile.com/quotes/kurt-vonnegut/he-predicted-i-remember-that-human-slavery-would-come-back-that-it/) [Kurt Vonnegut](https://sms4smile.com/quotes/author/kurt-vonnegut/) > [The most racist, nastiest act by the USA, after human slavery, was the bombing of Nagasaki. Not of Hiroshima, which might have had some…](https://sms4smile.com/quotes/kurt-vonnegut/the-most-racist-nastiest-act-by-the-usa-after-human-slavery-was-the/) [Kurt Vonnegut](https://sms4smile.com/quotes/author/kurt-vonnegut/) > [While we see the Course of the final abolition of human Slavery is onward, & we give it the aid of our prayers &…](https://sms4smile.com/quotes/robert-e-lee/while-we-see-the-course-of-the-final-abolition-of-human-slavery-is/) [Robert E. Lee](https://sms4smile.com/quotes/author/robert-e-lee/) > [America My Country: last nation on earth to abolish human slavery; first of all nations to drop the nuclear bomb on our fellow human…](https://sms4smile.com/quotes/edward-abbey/america-my-country-last-nation-on-earth-to-abolish-human-slavery/) [Edward Abbey](https://sms4smile.com/quotes/author/edward-abbey/) ## More by David Christian > [“It was possible to borrow British technology, and increasingly governments began to promote development. By the end of the nineteenth century, governments and large…](https://sms4smile.com/quotes/david-christian/it-was-possible-to-borrow-british-technology-and-increasingly/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [“the conquests of the Achaemenid and Hellenistic dynasties encouraged commercial and intellectual exchanges reaching from central Asia to India to the western Mediterranean. In…](https://sms4smile.com/quotes/david-christian/the-conquests-of-the-achaemenid-and-hellenistic-dynasties-encouraged/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [“So, as networks expand in size, their potential intellectual synergy increases much faster: “larger and denser populations equal faster technological advance.”](https://sms4smile.com/quotes/david-christian/so-as-networks-expand-in-size-their-potential-intellectual-synergy/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [“typical modern households live in urban environments where they earn incomes through some form of wage work and buy food produced by others. 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This, we will see, is the characteristic pattern of all such…](https://sms4smile.com/quotes/david-christian/contain-into-new-durable-configurations-which-can-handle-huge-energy/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [We, as extremely complex creatures, desperately need to know this story of how the universe creates complexity and why complexity means vulnerability and fragility.](https://sms4smile.com/quotes/david-christian/we-as-extremely-complex-creatures-desperately-need-to-know-this-story/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [If, in schools, we keep teaching that history is divided into American history and Chinese history and Russian history and Australian history, we're teaching…](https://sms4smile.com/quotes/david-christian/if-in-schools-we-keep-teaching-that-history-is-divided-into-american/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [An egg is a beautiful, sophisticated thing that can create even more sophisticated things, such as chickens. And we know in our heart of…](https://sms4smile.com/quotes/david-christian/an-egg-is-a-beautiful-sophisticated-thing-that-can-create-even-more/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [“Earth, for example, is made up of oxygen (almost 50 percent) and smaller amounts of iron (19 percent), silicon (14 percent), magnesium (12.5 percent),”](https://sms4smile.com/quotes/david-christian/earth-for-example-is-made-up-of-oxygen-almost-50-percent-and-smaller/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [“most of human history (chronologically speaking) has taken place in communities quite innocent of state power.”](https://sms4smile.com/quotes/david-christian/most-of-human-history-chronologically-speaking-has-taken-place-in/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) > [“what we can see may constitute no more than 10 percent, and perhaps as little as 1 percent, of the matter in the universe.”](https://sms4smile.com/quotes/david-christian/what-we-can-see-may-constitute-no-more-than-10-percent-and-perhaps-as/) [David Christian](https://sms4smile.com/quotes/author/david-christian/) [Explore all 86 David Christian quotes ](https://sms4smile.com/quotes/author/david-christian/) ## More Fossil fuel quotes > [Fossil fuels, including oil, are running out and supplies are getting harder to find. 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