“The water is in the river” takes the water as given and tells you where it is. “There is water in the river” reverses that: the river is the setting and the water is the news. Saying that something exists therefore reuses the machinery for saying where it is, and languages differ in how much they change along the way — some leave the locational predicate untouched, some add a placeholder subject, some borrow the possessive verb, and some keep a predicate for existence alone. The choice often splits by animacy and by number.
A preverbal negator weakens and is reinforced by an extra element, often a minimizer like “step” or “thing”. The reinforcer is reanalysed as the negator itself, then weakens in turn, and the cycle starts again.
A dedicated negative existential (“there is no X”) arises beside the ordinary negator, then spreads from existential sentences into verbal negation until it becomes the standard negator itself. Croft distinguishes six synchronic types — A, A~B, B, B~C, C, C~A — and the languages below sit at different points along the drift.
Latin habeō litterās scrīptās means “I have the letter in a written state” — a description of how the letter is now. That sentence became French j’ai écrit la lettre, which reports the writing rather than the letter, and in speech it is now the plain past: the old simple past has gone out of use. The same road runs from Old Japanese -tari to modern -ta. English started down it and stopped: have written is still a perfect, and cannot be used with yesterday.
Verbs of hearing and listening repeatedly grow a sense of obeying. The pattern recurs from Mandarin tīnghuà and Japanese iu koto o kiku to Latin oboedīre, built on audīre “to hear”, behind French obéir and English obey.
Verbs of seeing repeatedly become markers of attempting. Japanese 食べてみる “eat and see”, Korean 먹어 보다, Mandarin 試試看, and the Turkic converb + kör- constructions all say “do it and see” for “try doing it”; Voinov (2013) traces the co-lexification across Eurasia, New Guinea, India, and West Africa.