In conventional histories of English, the development of a discrete definite article in the late Old English and early Middle English periods has been barely touched upon. On many occasions the has been seen as an introduction from outside the native grammatical system; why such an introduction should have been felt necessary has rarely been discussed, however. The author of this study addresses this problem, focusing on the following issues: - the breakdown of inflectional morphology in the paradigms of the demonstrative pronouns: ambiguity in ending - the breakdown of grammatically significant root vowel distinctions in the paradigms of the demonstrative pronouns: ambiguity in form - the development of an absolute formal distinction between the and that: paradigm fissure - whether any or all of these developments have been caused, or encouraged, by contact between Old English and Old Norse