The formation of the prepositional pronouns / pronomi tonici will be discussed in relationship to their most important function, their use with prepositions.
pronomi tonici / prepositional pronouns
He has done it for me. Lo ha fatto per me.
He have said it to you. Lo ha detto a te.
He doesn' t know it from us. Non lo sa di noi.
With him it is possible to talk. Con lui si può parlare.
It doesn' t matter for us. Per noi è uguale.
He never speaks about what has happened. Non parla mai di ciò che è successo.
The prepositions above serve only as examples, it works the same way with every preposition. If we look at the prepositions above we see a, which is not only used to describe a direction (Vado al cinema <=> I go to the cinema), but to form the dative as well (Do il libro a Maria <=> I give the book to Maria). From that we can deduce, that there are two different ways to form the dative.
I give him the book. (I give the book to her.) Gli do il libro.
Do il libro a lui.
I tell her the truth. (I tell the truth to her.) Le dico la verità.
Dico la verità a lei.
We never have spoken about the genitive (the door of the house <=> la porta della casa) until know, but it is easy to distinguish from the other cases (nominative, accusative and dative) and easy to form, because there is no reserved personal pronoun for the genitive, it is built with a preposition.
It is his car. È la macchina di lui. (or with a possessive pronoun: È la sua macchina.)
We never heard from him again. Non abbiamo più sentito parlare di lui.
Wir halten also fest, dass wir zwei verschiedene Möglichkeiten haben, den Dativ zu bilden und der Genitiv, wie im Französisch, Englischen und Spanischen auch, über eine prepositions gebildet wird.
The genitive is formed with di + personal pronoun / noun and the dative can be formed as well with a + personal pronoun / noun. The construction a + personal pronoun is used to put the stress on the indirect object.
But I have given it to him and not to you. Ma lo ho dato a lui e non a te.
He has told the history to us and not to you. Ma questa storia l' ha raccontata a noi e non a te.
I see you, but not him. Vedo te, ma lui non lo vedo.