"This book is not only important but riveting . . . All the letters are summarised here in English, and 25 are printed in full. None are translated. Williams has performed miracles in deciphering the handwriting. The printed text is readable and largely intelligible: it has been slightly cleaned up, such that philologists can trust the vocabulary, syntax, morphology and spelling (including abbreviations), but not the punctuation. There are no misprints in the English, so we can trust the Spanish text to be right. This is scholarship at its best." (Journal of Iberian and Latin American Studies, Vol. 7, No.2, 2001) "The edition itself is exemplary . . . In making this important documentation not only available, but also so readily accessible through his editorial labours, Dr Williams has made a significant contribution to the more informed appreciation of a critical moment in the fortunes of seventeenth-century Spain and Europe." (BSS, Vol. 79, 2002) “This book will therefore be invaluable to specialists, but it will also provide an inexpensive source base for university courses on Spanish history…. it is a particular pleasure to welcome Williams’s scholarly and accessible edition of the letters of one of the most important and neglected figures in the history of early modern Europe.” (MLR, 99.3, 2004)