Biographical studies focussing on a single person may be intimate in scale but themes on a grander scale are often engaged.  Getting the scale right overall – especially for a PhD thesis - involves the judicious selection and elaboration of possible themes. This paper draws on research towards a biographical study of the public servant and polymath Robert Randolph Garran (1867-1957), a leading figure in the making of the Australian Commonwealth, including the development of its dominion status within the British Empire-Commonwealth. Garran’s ‘public service’ encompassed bureaucratic, diplomatic, cultural and intellectual leadership in a developing framework of national, imperial and international institutions, offering a rich setting for addressing a number of themes in Australian history. But choices need to be made to ensure that the scale is right and the result is not discordant.