through informal channels. They illustrate competitive capitalism at its most efficient, with transaction costs reduced to a practical minimum, but they are feasible only when economies of scale are limited. Later career Marshall served as President of the first day of the 1889 Co-operative Congress. Over the next two decades he worked to complete the second volume of his Principles, but his unyielding attention to detail and ambition for completeness prevented him from mastering the work's breadth. The work was never finished and many other, lesser works he had begun work on – a memorandum on trade policy for the Chancellor of the Exchequer in the 1890s, for instance – were left incomplete for the same reasons. His health problems had gradually grown worse since the 1880s, and in 1908 he retired from the university. He hoped to continue work on his Principles but his health continued to deteriorate and the project had continued to grow with each further investigation. The outbreak of the First World War in 1914 prompted him to revise his examinations of the international economy and in 1919 he published Industry and Trade at the age of 77. This work was a more empirical treatise than the largely theoretical Principles, and for that reason it failed to attract as much acclaim from theoretical economists. In 1923, he published Money, Credit, and Commerce, a broad amalgam of previous economic ideas, published and unpublished, stretching back a half-century. Final years, death and legacy From 1890 to 1924 he was the respected father of the economic profession and to most economists for the half-century after his death, the venerable grandfather. He had shied away from controversy during his life in a way that previous leaders of the profession had not, although his even-handedness drew great respect and even reverence from fellow economists, and his home at Balliol Croft in Cambridge had no shortage of distinguished guests. His students at Cambridge became leading figures in economics, including John Maynard Keynes and Arthur Cecil Pigou. His most important legacy was creating a respected, academic, scientifically founded profession for economists in the future that set the tone of the field for the remainder of the 20th century. Marshall died aged 81 at his home in Cambridge and is buried in the Ascension Parish Burial Ground. The library of the Department of Economics at Cambridge University (The Marshall Library of Economics), the Economics