During his speech "Quit India", Mahatma Gandhi used connotations and diction to create a formal or informal writing style. For example, on the later part of his speech where he "talks" to the people regarding their behavior towards other nationalities, this is an example of the use of diction to imply an informal writing style. The paragraph before that where he discussed a little about what he read from a book about French Revolution, his tone there is a little bit formal compared to the former. This highlights the importance of connotation and diction when writing and delivering a speech.
