Standarisation

http://englishcowpath.blogspot.co.uk/2012/04/prescriptivism-and-descriptivism-in.html

During the Renaissance periods (16th & 17th Century) when culture and the arts were booming, prescriptivism took a rise in and became important in society. Establishing 'correct' spelling, punctuation and grammar refined the language and distinguished between social classes (much like RP and Estuary English). 

Robert Lowth (1710 - 1787) was a strong prescriptivist who wrote several books dictating rules and giving grammatical order (based largely on studies of Latin)

Joseph Priestly (1733 - 1804) held the opposing opinion (descriptivism), as an empirical scientist he considered observation to be of high importance, much like evolution. He published a book at a similar time to Lowth, based from Latin principles, he found strong attraction to simplicity and wished to apply it to language. He famously said; ''I think it not only unsuitable to the genius of a free nation but in itself ill-calculated to reform and fix a language''.

Dr Johnson's Dictionary was publish in 1755, eight years after the proposal. During this time Johnson's goals had shifted, he'd begun to take a descriptivist stance as he recognised that language change was continuous and that the job of a lexicographer was 'to register the language' not to fix it.

Although, it did serve to 'fix' and regularise the language for the following 150 years until the publishing of the Oxford English Dictionary.