An interesting mood

Let's talk about one of Esperanto’s interesting verb moods: the “U-mood”. Most English books seem to call it the imperative mood. But on page 67 of “Being Colloquial in Esperanto”, David Jordan points out that its functions include things that could be considered “imperative”, “volitive” or “subjunctive” when comparing to how these moods are used in some other languages. If this means nothing to you, no worries, I’m gonna explain.

A brief (and coarse) statement of what is meant by a “verb mood”:

Let's with verb "tenses". Tenses are ways of modifying a verb (like “to hope”) so that it is in the past, present or future. Well, a “mood” is just another way of altering verbs to distinguish some other detail. Mood shows how the speaker considers the action to be aligned with reality, desire, or intent. The “indicative” mood is the simplest, and it shows that the action was, is or will occur: a fact. It’s the mood you get used to first (in Esperanto verb endings in indicative are -as, -is and -os for example). The reason the mood we’re interested in is called the U-mood in Esperanto, is because it involves putting the ending “-u” on the verb: esperi "to hope", goes to esperu).

So, combining what I’ve read in section 12.1.3 in “Being Colloquial in Esperanto”, on this PMEG page, this one too,  and around the Lernu forums, here’s how I reckon one uses the “u-mood”.

A verb in the u-mood generally corresponds to an action/state that is not a fact/real, but that is desired, ordered, or aimed for.

You can use it for direct commands (like the “imperative” mood):

kuru!
run!

pafu lin!
shoot him!

Here, you are implying the pronoun “vi” (“you”). In other words, there is a person you’re commanding; you’re telling them to run or shoot him. A common word for “please” in Esperanto is usually used in the U-mood (since you’re expressing desire):

bonvolu helpi min! 
please help me!

You can include a pronoun to make indirect commands. These often have many different translations, including words like “let” or “should”, or “ought” or “may”. They show a desire for the action, or that that action should be. In a full sentence or scenario, context will normally reveal which nuance is appropriate, but extra little words could also clarify.  So (including examples from the sources):

georgo faru ĝin!
let George do it!

li parolu 
let him speak, he should speak

ni manĝu! 
let’s eat!

oni ne provoku melon 
one shouldn’t (oughtn’t) provoke a badger.

ŝi belu, kaj mi ŝin forgesu 
let her be beautiful and let me forget her

I love ŝi belu, so NEAT. That’s grammar-gasm material right there.

The U-mood is also used in phrases introduced by ke (“that”) after a verb which expresses desire, a strong wish, request or command. The phrase introduced by ke is called a subordinate clause; the verb in this clause should be in the U-mood. This usage corresponds to some uses in other languages of the “subjunctive” mood.

mi petis ke vi ne provoku la melojn
I asked you to not provoke the badgers! *(literally: I asked that you not provoke the badgers)

mi volis ke vi alportu al mi lin vivanta!
I wanted you to bring him to me alive!

Note that you don’t need the U-mood after an expression of hoping (like, say, in Spanish with the subjunctive):

mi esperas ke vi venos
I hope that you will come

However, if you want to add the nuance that the phrase is desired as well as hoped for, then you might use it:

mi esperas ke vi venu 
I hope and want that you come

Furthermore, the U-mood should be used after por ke “in order that”, “in order to”, “so that”. Since the phrase that follows will always be what is aimed or desired.

mi aĉetis glavon por ke mi venku la melojn 
I bought a sword, so that I might defeat the badgers

I don’t think I’ve missed anything major… But do let me know if I have! 

* I’ve always jumped at the chance to unashamedly split my infinitives; I thoroughly enjoy doing so.