Chapter 1 covers the concept of chain-shifts and how they have been explained, and suggests that instead of merely looking at systems in explaining shifts, we should look for recurring types of phonetic change and examine why such types recur. The topic of the study is long-vowel change in Middle English and early Modern English, in the period c. 1050-1700. Some of these changes have been subsumed under the title ‘The Great Vowel Shift’, which is thought to be unrelated to a set of supposedly earlier changes that also affected the OE long vowels, i.e. those affecting OE ȳ, OE ǣ , OE ā, and OE ēo. To assess the dates, chronology and loci of all these changes, spelling evidence has been extracted from LAEME, LALME and SMED, three corpora of ME texts, which have been localised to within one of the Mediaeval counties of England. Some additional sources have also been exploited. The reasons why the traditional interpretation of the GVS are also presented. Finally, Chapter 1 discusses how and to what extent spelling may be used as evidence of sound-change.