Carissima (in veritate!) Pacis Puellae.
Gratias tibi, ut semper, quamvis fatendum sit explicationem tuam tantum difficilius intelectam difficiliorem intellectu esse. Nonnumquam opinor grammaticam in lingua vulgata explicare excutereque melius fuisse.
Agreed. I did most of it in Latin because we're in "speak Latin", but well, it's true that it's easier both to explain and to understand explanations in English. So, what I meant here:
4.
Sed quaestio est (mihi saltem) an participio ita uti possim :
eius (hic id pono tantum ad ambiguitatem vitandam, ne videatur adiectivum huius "muris" esse cum pronomen sit pro "participio") subtantivum
suum (adiectivo reciproco ("reflexive") hic uti non oportet, nam hoc "participio", cuius "substantivum" est, subiectum sententiae non est) “muris...
Substantivum suum: you shouldn't use the reflexive
suum there, because the "owner" of the substantive, that is
participio in the previous sentence, is not the subject of the the sentence
substantivum suum "muris" sequitur.
The reflexive possessive adjectives
suus, a, um and the reflexive pronouns
se, sibi are used, first, when directly referring to the subject of the clause they are in:
Puer cani suo aquam dat = the boy gives water to his (own) dog; the reflexive is used because the owner of the dog,
puer, is the subject of the sentence. If it was "his dog" not as the boy's dog, but someone else's dog, you wouldn't say
suo, but the genitive of a demonstrative, like
eius or
illius:
puer cum amico loquitur et cani eius aquam dat = the boy is talking with his friend and gives water to his (= the friend's) dog.
Puer ad puteum it ut aquam hauriat, nam canis eius sitit = the boy goes to the well to draw water, for his dog is thirsty: here you don't use the reflexive, because the owner of the dog,
puer, is not the subject of the clause
canis eius sitit, it's
canis.
However there are cases where the reflexive is used while not referring directly to the subject of the very clause it is in, but to the subject of the clause on which it depends; those cases are when the clause depends on indirect speech, verbs of saying, ordering, wishing, saying, feeling, and purpose clauses.
Puer cani suo aquam dari vult = the boy wants water to be given to his dog:
puer is not the subject of the clause (acc-inf) in which
suo is (the subject is
aquam), but it is that of the verb on which that clause depends,
vult.
Puer canem suum sitire ait = the boy says his dog is thirsty: same thing here,
puer is not the subject of the clause
suum is in, but it's that of the verb on which that acc-inf clause depends,
ait.
Puer aquam haurit ut canis suus bibat = the boy draws water so that his dog may drink: puer is not the subject of the clause
canis suus bibat, but this clause is a purpose clause depending on the clause in which
puer is subject.
On the whole, the reflexive is used without referring directly to the subject of the clause it is in when this clause depends on a verb which in some way introduces something coming from the thought of the subject; if it's something they say, order, feel, aim at...
There can be some exceptions, but these are the principal rules.
In your sentence, there's nothing of all that: that's why the demonstrative in genitive was needed and not the reflexive possessive.
When correcting your sentence, I didn't just replace
suum by
eius while leaving it at the same place, but I put it before
substantivum, to avoid amibiguity, because seeing that the next word
muris was a genitive,
eius could have been interpreted as going with it, and a change of word order hinted more to the right interpretation that
eius was a pronoun representing
participio, and not an adjective in agreement with
muris.
(Quomodo nomine anglice indeclinabile redditur possessio?: “New Latin Syntax ab Woodcock scriptus”? )
Mmm, yes.
De Woodcock can do too, I think, it just has a late Latin flavour. But
scriptum, unless you say
liber.