-zu and -sou

Hi. I wonder if anyone can give me some ideas on the -zu and -sou form of verbs. -zu is like something you have not done, right?

Thanks.

-zu is the literary form of -nai.
Preceding verbs and adjectives must be also the literary form.

hashira-nai = hashira-zu (not run)
mi-nai = mi-zu (not see)
ko-nai = ko-zu (not come)
shi-nai = se-zu (not do)

taka-ku-nai = taka-kara-zu (not high)
utsukushi-ku-nai = utsukushi-kara-zu (not beautiful)
shizuka-de-nai = shizuka-nara-zu (not quiet)

If a noun follows it becomes -nu or -zaru.

kaera-nu hito / kaera-zaru hito (person who doesn't return; i.e. dead person)

-sou is short for -sou da / -sou desu.

It means "it seems", "it looks", "it appears" etc. when it follows the
same form as -masu of a verb (e.g. hashiri-) or the stem of an adjective
(e.g. taka-).

kare wa hashiri-sou da. (It seems he will run.)
kono shohin wa taka-sou da. (This item seems to be expensive.)
kono heya wa shizuka-sou da. (This room seems to be quiet.)

Alternatively, it means "they say", "it is said", I hear" etc. when it
follows the dictionary form of a verb (e.g. hashiru) or an adjective
(e.g. takai).

kare wa hashiru-sou da. (I hear he will run.)
kono shohin wa takai-sou da. (I hear this item is expensive.)
kono heya wa shizukada-sou da. (I hear this room is quiet.)

Oh I see... Thanks a lot, meringue4 =)

As many of these words, context is vital. In one example, kaesu - give back, uses su. Another, kaesu means hatch chickens, probably in a different part of the sentence.

But seem to be simpler & usable version of these words, without the su, as such, as kaeri - come back and is much easier to use & apply, as I believe everything is linked with 'te', 'ru' or 'masu' for verbs that are easily recognised.

Hatch chickens, bring back life, associations with water-life bringing (sui), I'm not sure if are classified as verbs in Japanese, but a natural occurance or description unless there is no verb in the sentence. One can't have many verbs or mid sentence.

soo desu. Agree is.

desu is the verb
- at end
- means is

soo is then a relationship word, like doozo, becomes a verb on its own, but not in a sentence and equally a part of communication like bowing, and these words are more likely to have long vowel sounds that can be more expressive when one wants to be.