For Smith language was a crucial entry point to the development and explication of a projected science of man… Smith sees effective communication as requiring what he calls perspicuity and propriety. Perspicuity is to be achieved through a plain and unadorned style, in contrast to — a favourite target — the artificial and pompous labourings of Lord Shaftesbury in his ‘dungeon of metaphorical obscurity’. A perspicuous language is one that clearly projects, but also thereby reveals, the thoughts of its speakers. Propriety, or correctness in the use of language, fits language both to the speaker’s natural character and communicative intent on one side and to the expectations of the audience on the other. Effective communication requires the speaker to anticipate what effect their words will have on the hearer. Propriety thus carries with it a host of tacit assumptions about norms of grammar and presentation, about the speaker’s persona the occasion ,social context and audience; and it is through propriety that sympathy, that communicative bond between speaker and audience, is conveyed.
As Smith put it, ‘when the sentiment of the speaker is expressed in a neat, clear, plain, and clever manner, and the passion or affection he is possessed of and intends, by sympathy, to communicate to his hearer, is plainly and cleverly hit off, then and then only the expression has all the force and beauty that language can give it.’…
From Jesse Norman’s Adam Smith: Father of Economics.
beyond the times 