Question: In English, we can say "one must do this" or "one should do that", as a way of referring to any person, not just one person in specific. Can *homo* be used in a similar fashion in Latin (particularly in Classical Latin). Some example sentences:

> 
> One should drink in moderation.
> 
> 
> 

> 
> One must not eat the yellow snow.
> 
> 
> 

There was an answer to a translation question where the [lack of an impersonal pronoun](https://latin.stackexchange.com/a/16222/5056) was mentioned, so I'm curious if this usage of *homo* would work.

Answer: 
The use of *homo* as a genuine indefinite pronoun is definitely not good Classical Latin, but *homo* did have indefinite meaning from the very beginning, and by the Christian era Vulgar Latin was clearly well on its way to developing it into a true pronoun (cf. the Vulgate's *non in solo pane vivit homo*, often translated as "*one* does not live on bread alone"). Clear lines can be hard to draw, however; it's difficult to find a use of *homo* that can *only* be pronominal.

It's probably not the case that *homo* became a true pronoun before the separation of the Romance languages, but it was certainly close enough already that it only needed a gentle push to become one later on.  

Probably the most famous surviving reflex is French *on* (from the nominative; compare that to the noun *homme*, from the accusative); for a while it was commonly believed to be the only one, but actually Catalan has *hom* (with or without the indefinite article *un*), and apparently a few Italian dialects still use *uomo*. The heyday of Italian pronominal *uomo* was the 13th century to the 15th, with only one attestation prior to that, in the 12th. Old Spanish also used *omne/hombre* (formally unambiguously from the accusative) as an indefinite pronoun, but stopped in the 16th century; it also doesn't seem to have done it before the 12th. The Eastern Romance does not preserve it, if it ever had it.

(Because of the prominence of French *on*, Germanic influence was often cited as the origin of the pronominal use of *homo* (cf. Dutch *men*, German *man*, Middle English *man/men*, all 3sg indefinite pronouns originating in the unstressed version of a word meaning 'man'), but given its original indefinite meaning, it's really not necessary.)

Classical Latin typically uses passive constructions (like the gerundives of the other answer) or 3rd person plurals without expressed pronouns (e.g. *dicent* often becomes "on dit" in French and "men zegt" in Dutch, though English does also render it as "they say") where other languages might use their impersonal or indefinite pronouns.
I'd express this as **bibendum est cum temperantia** and **nives albicerae edendae non sunt** without any need for an impersonal pronoun.