Chemists now use the term “curly arrows” as a language to describe the electronic rearrangements that occur when a (predominately organic) molecule transforms to another – the so called chemical reaction. It is also used to infer, via valence bond or resonance theory, what the mechanistic implications of that reaction are. It was in this latter context that the very first such usage occured in 1924[cite]bx4svt[/cite] taking the form of a letter by Robert Robinson to the secretary of the Chemical Society and “read” on December 18th 1924. The following diagram was included: