Sorby’s Presidential Address of 1897 on the structure and origin of limestones was essentially an interim report of research in progress. His petrographic approach to limestones, stemming from three decades of research, laid the foundations for a wide range of research lines, some of which were not fully exploited for almost a century, such as fluid inclusion studies in diagenesis. The significance of many of his discoveries (e.g. that some Jurassic ooids and Palaeozoic corals were originally calcitic) had geochemical implications that have only recently achieved research prominence (e.g. CO2 and the ‘greenhouse’ Earth). In addition, Sorby’s legacy was the example of his peerless approach to research, applying ruthless empiricism to the problem at hand. In the case of limestones, this involved an application of meticulous descriptive petrography and innovative experimentation. His approach to understand more fully the complex problems posed by carbonates remains unsurpassed, involving a thorough integration of detailed observation, imaginative thinking and judicious use of analytical techniques.