Before the 18th century, scientists and non-scientists alike assumed that the material substance of living organisms was fundamentally different from that of non-living things — organisms and their products were considered organic by definition, while non-living things were mineral or inorganic.
With the invention of chemistry in the late 18th century, scientists uncovered the incoherence of the traditional distinction: all material substances are constructed from the same set of chemical elements. Today we understand that the special properties of living organic matter emerge from the interactions of a large variety of large molecules built mostly with atoms of carbon, oxygen, and hydrogen.
Chemists now use the word organic to describe all complex, carbon-based molecules—whether or not they are actually products of an organism or products of laboratory synthesis. But many educated people in Western countries think that only some crops and cows are organic, while all others are not. How can one simple word — organic — have such different meanings?
Through the 19th and 20th centuries, increased scientific understanding, technological innovations, and social mobility changed the face of American agriculture. Large-scale farming became more industrialized and more efficient. In 1800, farmers made up 90% of the American labor force; by 1900, their proportion had decreased to 38%, and in 1990, it was only 2.6%. However, not everyone was happy with these societal changes, and there were calls in the United States and Europe for a return to the preindustrial farming methods of earlier times.