"La" is for "a feminine person" or for "a feminine noun" in general?
 

Is direct object pronoun "la" just for "a feminine person"? or "la" can be used for "feminine noun" in general?

For example suppose below sentence:

The mad man told himself nonsense. = El loco se dijo una tontería.

Now I want to use a pronoun instead of "una tontería". which sentences can be correct?:

"se la dijo." or "se lo dijo."

Se la dijo.

In Spanish, we disguiss between OD and OI. It doesn't matter if we're reffering to a person or an object. The only exception is "the personal a".

Good luck!

Thanks for reply,

could you give me an example for that exception?

Any noun that functions as an indirect object (objeto indirecto = OI) is introduced with the preposition "a". It doesn't matter whether the noun identifies a person or not, and it doesn't matter whether the noun is definite and specific or not.

On the other hand, a noun that functions as a direct object (object directo = OD) may or may not be introduced by the preposition "a".

When a direct object refers to a specific person or animate being that is viewed as a person, one normally introduces that direct object with the preposition "a". (This use of the preposition "a" is commonly called "personal a".) For example:

"Busco a una secretaria que habla español" = "I'm looking for a secretary who/that speaks Spanish".

Using the preposition "a" to introduce the direct object "una secretaria" in combination with using the indicative mood in the relative clause unambiguously indicates that the secretary in question is a particular woman known to the subject who is a secretary and who can be identified by the fact that she speaks Spanish. In this case the direct object refers to a specific person.

On the other hand, when a direct object does not refer to a specific specific person or animate being, normally one does not use the preposition "a" to introduce the direct object. For example:

"Busco una secretaria que hable español." = "I'm looking for a secretary who/that speaks Spanish".

Not using the preposition "a" to introduce the direct object "una secretaria" in combination with using the subjunctive mood in the relative clause unambiguous indicates that the speaker does not know whether or not such a person exists.

Another example:

"Busco la pluma de mi amiga" = I'm looking for my friend's pen.

The direct object is the inanimate noun "la pluma". This is a specific direct object, but it's not viewed as a "person" in any sense, and one does not introduce this direct object with the preposition "a".

There are occasions when one may or must use the preposition "a" to introduce a direct object that is non-living. This typically occurs when both the subject and the direct object are non-living things and it would not otherwise be clear which one is the subject and which one is the direct object; the one introduced by the preposition "a" is the direct object, and the other one is the subject.

Thanks wrholt,

I think i somewhat understood your information except the last paragraph. Please give me an example for that.

Also I would like to know answer of these question explicitly with yes or no.

1- Can "la" be used instead of "inanimate feminine noun"? like my sentence that it used instead of "una tontería".

2- If the sentence of: "Se la dijo." is correct, then "la" is I.O pronoun Or D.O pronoun?

1) Yes.

2) It's a DO pronoun. "La" never works as a IO.

Here's an example quoted from Butt & Benjamin, "A New Reference Grammar of Modern Spanish", 4th edition (2004):

Es difícil saber en qué medido afectó esto a la economía cubana = It is difficult to know to what extent this affected the Cuban economy

Compare this to:

Es difícil saber en qué medida afectó esto la economía cubana = ?

The version without the preposition "a" is ambiguous: the subject could be either "esto" or "la economía cubana": we can't be sure whether "the Cuban economy" affected "this" or whether "this" affected "the Cuban economy".

very good and professional answer!

Is it possible to find this edition of book in internet freely :).
I have the second edition of this book. how much change is done in this edition?

Amazon lists multiple copies of several editions of Butt & Benjamin. You may find other vendors on-line too. I believe that there is a now a 5th edition that takes into account more recent changes in RAE recommendations.