To a superficial observer, alterations in syntax attack without warning. Like a hidden spider's web, they lie in wait and stealthily catch on to pieces of language, which are suddenly entrapped in inescapable silken threads.

Syntactic change – change in the form and order of words – is therefore sometimes described as ‘an elusive process as compared to sound change’. Its apparently puzzling nature is partly due to its variety. Word endings can be modified. Chaucer's line And smale foweles maken melodye shows that English has changed several of them in the last 600 years. The behaviour of verbs can alter. Middle English I kan a noble tale ‘I know a fine story’ reveals that can could once be used as a main verb with a direct object. And word order may switch. The proverb Whoever loved that loved not at first sight? indicates that English negatives could once be placed after main verbs. These are just a random sample of syntactic changes which have occurred in English in the last half-millennium or so.

It's hard to chart syntactic change. If a schoolboy says I didn't bash Pete, I never bashed Pete, are the two different negative structures interchangeable, signalling that a change may be in progress? Or is the second statement emphatic, meaning: ‘I really and truly didn't bash Pete’? It's almost impossible to tell.