Around the mid-nineteenth century, it became commonly known that the deficits of brain softening had sometimes been preceded by temporary attacks of the same kind (hemiplegia, disorders of language). In the middle of the twentieth century, Fisher recognized that episodes of monocular blindness, identified in 1898 as embolic (Knapp), were also potential harbingers of cerebral ischaemia. Studies addressing the risk of stroke after such warnings, conducted in the 1960s and early 1970s, were sparse and difficult to interpret.