The first label is "most prebiotic experiments", indicating that prebiotic experiments that form the monomeric building blocks of life or their precursors tend to have products at concentrations of ≳ 10 -3 mol/L (see Walton et al. and references therein). The limits for the products of a multi-step synthesis to participate in subsequent reactions are around ≳ 10 -6 mol/L. Most detection techniques will not operate reliably for concentrations below 10 -9 mol/L 29 meaning that most current or near-future prebiotic investigations will not be able to empirically test scenarios that involve concentrations much lower than this. Instead, non-standard approaches, involving theoretical models or novel analytical techniques, will be required. There will be some concentration, not yet precisely determined, below which prebiotic synthesis is statistically impossible regardless of the yield. Returning to the farming analogy, prebiotic synthetic chemists are those who seek to farm in uncultivated soil. At times, the task may seem daunting, akin to trying to grow crops in soil that has never been tended. However, one of the principles of do-nothing farming is that even uncultivated soil is still regulated by nature and can turn out to be more fertile than the farmer often imagines. Here the prebiotic chemist's soil is liquid water. Liquid water is a very challenging solvent for organic chemistry due to its tendency to break down many prebiotically relevant compounds, including the precursors to the monomeric building blocks, such as hydrogen cyanide, other nitriles, and aldehydes. Many of these hydrolysis reactions are effectively irreversible. Water also poses a challenge for polymerization reactions involving these building blocks, as they require dehydration, a process that is thermodynamically disfavored in water. These challenges underscore why numerous prebiotic syntheses focus on eliminating water through techniques like freezing and drying. In almost every other domain of synthetic chemistry the problematic nature of water would not pose an issue as any efficient method to get from reactant to product is allowed.