Yeah, I made that genitive up, but only to describe a real phenomenon in Latin! Some adjectives of likeness, nearness, and belonging that normally take the dative will occasionally take a possessive genitive. This transition is especially common where the adjective approaches the force of a noun.
Fuit hōc quondam proprium populī Rōmānī: this was once peculiar to the Roman people. (~a peculiar trait of)
Fuit semper amīcus Cicerōnis: he was always friendly with Cicero. (~a friend of)
Adeō patris similis es: you’re just like your master. (~a chip off the old block)
Here’s the full list of adjectives that perform this function—
aequālis, aequāle: of the same age (~a contemporary of)
affīnis, affīne: related to by marriage (~kinsman of)
aliēnus, -a, -um: belonging to another (~a stranger to)
cōgnātus, -a, -um: fellow-born (~kinsman of)
commūnis, commūne: common to (~kinsman of)
cōnsanguineus, -a, -um: sharing a bloodline (~kinsman of)
contrārius, -a, -um: opposite (~the opposite of)
dispār: unlike (dispar suī, in philosophical diction)
familiāris, familiāre: of close relation (~intimate of)
fīnitimus, -a, -um: adjoining (~neighbor of)
inimīcus, -a, -um: hostile to (~enemy of)
necessārius, -a, -um: connected with (~component of)
pār: equal to (~a match)
pecūliāris, pecūliāre: personal (~peculiar trait of)
propinquus, -a, -um: neighboring (~neighbor of)
proprius, -a, -um: personal (~peculiar trait of)
sacer, sacra, sacrum: holy (~holy with respect to some deity)
similis, simile: alike to (~spitting image of)
superstes: surviving (~survivor of)
vīcīnus, -a, -um: neighboring (~neighbor of)
Note that this genitive construction is actually more common for proprius, -a, -um than the dative construction.
Similis with the genitive is especially common with personal pronouns (meī, tuī, suī) and within the fixed phrase vērī similis (probable).
Like A&G, I would like to conclude my series on i-stems with a short assessment of the basic rules and variations associated with the i-stem class.
A&G paint a picture of cultural amnesia regarding Roman relations with the i-stem. As I have shown in previous posts, in all but the genitive plural (ium), and the neuter accusative/nominative plural (ia), the unique i-stem endings are rare or optional. (cf. the status of English ‘who/m’).
The nominative singular could be -is (sitis, is) but also ēs/-s/–x, etc.
The accusative singular could be -im but also -em.
The ablative singular could be -ī or it could be -e.
The accusative masc/femplural might be -īs but it’s usually -ēs.
This post considers places where the Dative of Agent invades what would normally be constructions suitable to the Ablative of Agent.
With Passive Perfect Participles
With passive verbs, the Dative of Agent is most common with perfect passive participles, especially when these are virtually adjectival.
It has been deliberated and established by me: mihi dēlīberātum et cōnstitūtum est.
This has been provided for by you: tibi haec prōvīsa est.
The lights have made me dizzy: lūcibus cālīgātus sum.
Note that, with the final expression, lūcibus may be either Dative or an Ablative of Instrument (but not an Ablative of Agent, since there is no ā/ab). In this case, assume it’s an Ablative of Instrument, which is altogether more common, especially with something inanimate like ‘lights.’
– With Passive Verb
The Dative of Agent is not unheard of with standard passive verbs, especially with the poets.
He is not seen by anyone: nōn cernitur ūllī.
He was favored by the nymph: Nymphō fovēbātur.
The construction ‘it seems to x‘ is expressed with videor, vidērī, visus + Dative of Agent.
He seemed to me a horse with wings: mihi equis cum ālīs vidēbātur.
It seemed otherwise to the gods: dīs aliter vīsum est.
It seems to me that you are a slob: sordidus mihi vidēris.
According to AG, probāre takes a Dative of Reference, but it’s so regularly attached that it seems like a Dative of Agent. I’m not sure I buy this, but here’s what they mean:
This view was approved by both him and me: haec sententia et illī et mihi probābātur.
This plan was not approved by the majority: hōc cōnsilium plēris nōn probābātur.