This article argues against unnecessarily ‘scientific’ rigour in determining sources. Source study originated in Quellenforschung, a study of classical texts that mined an extant work for information about lost sources but ignored the work's own textual and contextual dynamics. Early source studies of Shakespeare similarly focused on a single source and one simple relation between source and play. Like nineteenth-century classical scholars, they insisted on quantifiable evidence and treated echoes as separate phenomena, as if they had had no effect on one another in the original process of being remembered and reused. Source study had no role in interpretation. The only important questions were: exactly how similar is each source line to its proposed Shakespearian echo? How many echoes are there?

Many accounts of sources still proceed this way but I argue instead for a contextual approach that studies each echo in the context of the original source from which it came, the play in which it supposedly landed and the other echoes from that source. My example is the Queen's Men's play, King Leir (1585–7?), long recognized as the primary source for Shakespeare's King Lear (1604/5). As critics continue to discover, the old play is the origin of many of its lines but the larger relationship between Shakespeare and Leir still remains to be examined. The following article collects all the Leir echoes together and adds a few, in order to see what Shakespeare borrowed from Leir.