EXPRESSIONS OF POSSESSION/OWNERSHIP INVOLVING OR NOT INVOLVING THE DATIVE, AND THOSE TIMES WHEN A DATIVE TRANSLATES TO A POSSESSIVE IN ENGLISH
1. DATIVE OF POSSESSION (PROPER)
A dative of possession, properly speaking, is when you have a noun or pronoun in the dative denoting the owner of a thing, while the thing possessed is found as the subject of a form of sum, the whole being equivalent in meaning to English "X has Y".
Example:
Publio duo filii sunt.
Literally, this means "To Publius two sons are". That is, two sons exist for Publius, two sons exist as a "possession" (in a very broad sense) of Publius's: what you would express in idiomatic English as "Publius has two sons".
A rather common mistake consists in extending this to expressions of ownership like "this or that is mine/yours, etc." or "this or that belongs to me/you, etc.": I have more than once seen people (and, to be honest, I myself made that mistake once or twice in the past!) translating a sentence of this kind with (what they imagined to be) a dative of possession; for example, translating "That book is mine" as liber ille mihi est. This is wrong. X mihi est conveys the idea of "I have X", not of "X is mine"/"X belongs to me". To convey the latter, you must use a possessive: liber ille meus est. If the owner in English is denoted by a noun (rather than by a possessive pronoun like "mine", "yours", etc.), as in "That books is my brother's"/"That book belongs to my brother", you use the genitive: liber ille fratris mei est.
The above explanations are perhaps sufficient for all practical purposes, but I would nonetheless like to add something concerning how the two constructions, aliquid alicui est and aliquid alicuius est, essentially differ: in aliquid alicui est ( "something is to someone" = "someone has something"), you are stating the existence of something as a certain person's possession, whereas in aliquid alicuius est ("something is someone's" or "something belongs to someone") you are stating that something, whose existence is already assumed, belongs to a certain person.
2. THOSE TIMES WHEN A DATIVE TRANSLATES TO A POSSESSIVE (MY, YOUR, SOMEONE'S, ETC.) IN ENGLISH
In some contexts, a dative (of reference) may seemingly translate to an English possessive; for example, in a sentence like this one:
Gaius mihi bracchium fregit.
Which is literally "Gaius broke the arm to me", but will translate into idiomatic English as "Gaius broke my arm".
Now, because "my" in the English translation seemingly corresponds to mihi in the Latin, some people will mistake mihi to be, in this context, simply equivalent to "my", and imagine that it goes bracchium just like "my" goes with "arm" in the English: they will think that bracchium mihi is equivalent to "my arm". That is not so, and thinking that it is will lead you to sometimes misuse the dative when writing or speaking Latin.
The truth is that English and Latin just express things differently here, and while anyone wishing to translate Latin into good English will translate Gaius mihi bracchium fregit as "Gaius broke my arm", that is not what the Latin literally means: not only does mihi not literally mean "my" (as is easy to understand; few people familiar with both words would err on this point), but also the relations between the words in the Latin differ from those in English (and this is what no few students fail at some point to understand properly, and what causes them to make mistakes in producing Latin). In the English, "my" goes with "arm", and "my arm" forms a unit. But in the Latin, mihi does not modify bracchium; rather, it goes with the verb fregit, and indicates who was affected by the action of breaking, to whom the breaking was done. It is not mihi bracchium = "the arm to me", but mihi fregit = "he broke to me". Gaius broke an arm, and he did it to me (mihi). This implies that it was my arm, but the Latin doesn't say it literally. English will, because that's its own manner, different from the Latin one*, of describing that sort of situation. English tells you whose arm it was, while Latin tells you to whom the arm-breaking was done.
It is important to grasp this if you want to produce correct Latin, because if you mistakenly think that a dative may just stand for a possessive and modify a noun in the same way as a possessive does, you will end up using the dative where it is not at all appropriate. For example, it would be rather bizarre to translate "I saw Publius's dog yesterday" as canem Publio heri vidi, because seeing his dog isn't something that you did to Publius. The dative Publio has to go with the verb and indicate to whom the thing was done; it can't modify canem as "Publius's" modifies "dog" in English; for that you need a genitive (canem Publii heri vidi).
*I mean in this particular sentence. It is also possible to find possessives in similar situations in Latin.
I hope this post was helpful. If you're still unsure about something, you can always create a thread with your questions in the appropriate subforum.
1. DATIVE OF POSSESSION (PROPER)
A dative of possession, properly speaking, is when you have a noun or pronoun in the dative denoting the owner of a thing, while the thing possessed is found as the subject of a form of sum, the whole being equivalent in meaning to English "X has Y".
Example:
Publio duo filii sunt.
Literally, this means "To Publius two sons are". That is, two sons exist for Publius, two sons exist as a "possession" (in a very broad sense) of Publius's: what you would express in idiomatic English as "Publius has two sons".
A rather common mistake consists in extending this to expressions of ownership like "this or that is mine/yours, etc." or "this or that belongs to me/you, etc.": I have more than once seen people (and, to be honest, I myself made that mistake once or twice in the past!) translating a sentence of this kind with (what they imagined to be) a dative of possession; for example, translating "That book is mine" as liber ille mihi est. This is wrong. X mihi est conveys the idea of "I have X", not of "X is mine"/"X belongs to me". To convey the latter, you must use a possessive: liber ille meus est. If the owner in English is denoted by a noun (rather than by a possessive pronoun like "mine", "yours", etc.), as in "That books is my brother's"/"That book belongs to my brother", you use the genitive: liber ille fratris mei est.
The above explanations are perhaps sufficient for all practical purposes, but I would nonetheless like to add something concerning how the two constructions, aliquid alicui est and aliquid alicuius est, essentially differ: in aliquid alicui est ( "something is to someone" = "someone has something"), you are stating the existence of something as a certain person's possession, whereas in aliquid alicuius est ("something is someone's" or "something belongs to someone") you are stating that something, whose existence is already assumed, belongs to a certain person.
2. THOSE TIMES WHEN A DATIVE TRANSLATES TO A POSSESSIVE (MY, YOUR, SOMEONE'S, ETC.) IN ENGLISH
In some contexts, a dative (of reference) may seemingly translate to an English possessive; for example, in a sentence like this one:
Gaius mihi bracchium fregit.
Which is literally "Gaius broke the arm to me", but will translate into idiomatic English as "Gaius broke my arm".
Now, because "my" in the English translation seemingly corresponds to mihi in the Latin, some people will mistake mihi to be, in this context, simply equivalent to "my", and imagine that it goes bracchium just like "my" goes with "arm" in the English: they will think that bracchium mihi is equivalent to "my arm". That is not so, and thinking that it is will lead you to sometimes misuse the dative when writing or speaking Latin.
The truth is that English and Latin just express things differently here, and while anyone wishing to translate Latin into good English will translate Gaius mihi bracchium fregit as "Gaius broke my arm", that is not what the Latin literally means: not only does mihi not literally mean "my" (as is easy to understand; few people familiar with both words would err on this point), but also the relations between the words in the Latin differ from those in English (and this is what no few students fail at some point to understand properly, and what causes them to make mistakes in producing Latin). In the English, "my" goes with "arm", and "my arm" forms a unit. But in the Latin, mihi does not modify bracchium; rather, it goes with the verb fregit, and indicates who was affected by the action of breaking, to whom the breaking was done. It is not mihi bracchium = "the arm to me", but mihi fregit = "he broke to me". Gaius broke an arm, and he did it to me (mihi). This implies that it was my arm, but the Latin doesn't say it literally. English will, because that's its own manner, different from the Latin one*, of describing that sort of situation. English tells you whose arm it was, while Latin tells you to whom the arm-breaking was done.
It is important to grasp this if you want to produce correct Latin, because if you mistakenly think that a dative may just stand for a possessive and modify a noun in the same way as a possessive does, you will end up using the dative where it is not at all appropriate. For example, it would be rather bizarre to translate "I saw Publius's dog yesterday" as canem Publio heri vidi, because seeing his dog isn't something that you did to Publius. The dative Publio has to go with the verb and indicate to whom the thing was done; it can't modify canem as "Publius's" modifies "dog" in English; for that you need a genitive (canem Publii heri vidi).
*I mean in this particular sentence. It is also possible to find possessives in similar situations in Latin.
I hope this post was helpful. If you're still unsure about something, you can always create a thread with your questions in the appropriate subforum.
