<p>This diagram comes from Ayres and Kneese's 1969 publication on 'Production, consumption, and externalities', which included a detailed description of material flows and the weight of material production. This image represents the types and transformations of material flows as they move through a socio-economic system. It is interesting to note how particular concepts were more prominently featured that what is common nowadays, and how some terms have changed over time. There is a large box to depict various energy conversions (leading to the production of useful energy as well as emissions to air). What is now commonly referred to as biomass and biomass products was referred to as 'Products of Photosynthesis'. Interestingly, we can still recognize most of these flows in recent graphs, including net addition to stock (called increased inventory in this graph) as well as recycling. </p><p>Great to see how this image was produced by combining type writing and manually drawing labels and arrows. <br></p>