Thomas Harriot was one of the most distinguished scholars and scientists of his time. But his activities were so various and the accessibility of his prodigious remains so unevenly distributed that he has remained largely unknown to the generality of students of the period until the past generation. Even now, when a great deal of work has been done on him, and a generous and informative biography - by John Shirley - has been written, 1 he is hard to understand in his intellectual context. Americanists know him, even if only in a few aspects and not all of those fully; mathematicians know him, but many of the 8000-plus working sheets of his calculations and notes have still not been unravelled (many indeed are too fragmentary to yield to analysis); astronomers know him as a contemporary of Galileo whose own lunar observations in particular are of outstanding interest; and I could continue into other fields. It is not easy to place him in the general framework of the history of science, even if his primary importance may, in the end, prove, as has often been thought, to be that of a mathematician; but he was many other things as well. I would, however, take the risk of putting one general label on him which I think is useful in attempting to fit him into many of the categories in which he has a place. That attribute is 'problem-solver'. He appears to me to have been someone who, from his early manhood, was ready, when presented with a problem, however novel or apparently intractable, to seek a solution and who showed an astonishing versatility in doing so.