Grammar and linguistics. 17th-century illustration showing a theory of natural grammar, looking at prepositions relating to positions and motions in time and space. The figure at left and the circular regions at right are used to arrange and classify prepositions such as before, after, up, down, over, under, beyond, through, and above and below. The author attempts to distinguish between prepositions related to motion, ones related to rest, and those that can refer to both. Artwork from 'An Essay towards a Real Character and a Philosophical Language' (1668) by English clergyman and natural philosopher John Wilkins (1614-1672). In this book, Wilkins attempted to establish a universal language.