English prepositions are words – such as of, in, on, at, from, etc. – that function as the head of a prepositional phrase, and most characteristically license a noun phrase object (e.g., in the water). Semantically, they most typically denote relations in space and time. Morphologically, they are usually simple and do not inflect. They form a closed lexical category. Many of the most common of these are grammaticalized and correspond to case markings in languages such as Latin. For example, of typically corresponds to the genitive. History of the concept in English The history of the idea of prepositions inEnglish grammar writing can be seen as one of relative stagnation, only exceptionally interrupted by certain more influential authors... It was only in the second half of the twentieth century that the situation radically changed and since then, grammarians have introduced scientifically precise definitions and developed detailed and elaborate frameworks for their description.The word preposition is from "Latin praepositionem (nominative praepositio) 'a putting before, a prefixing,' noun of action from past-participle stem of praeponere 'put before'," the basic idea being that it is a word that comes before a noun. Its first known use in English is by John Drury, writing in Middle English on Latin grammar c1434. The meaning was essentially the same as the general idea today: a simple word preceding a noun expressing a relation between it and another word. William Bullokar wrote the earliest grammar of English, published in 1586. It includes a chapter on prepositions. His definition follows:A part of speech properly used prepositively, that is governing an accusative case set next after it (except sometime in verse it is set after his casual word) as, I go to the church: and is sometime postpositively used, that is, when it governeth the relative, that, or which, coming before a verb, whose governing preposition is set after such verb: as, this is the man whom we spoke of, or of whom we spoke; and is some time used in composition after a verb, but being severed from the verb by the adverb, not, or by an accusative case, may be said to be set in apposition adverbially. (p. 320; orthography has been modernized) Some grammarians, though, noted problems. In 1746, John Kirkby complains: "we have several instances of the same word being used at one time as a conjunction and at another time as a preposition."