When should I use "le" instead of "lo"?

Is there an easy way to know if we should use "le" or "les" instead of "lo", "los", "la", "las"?

I understand that I say,"lo tiré [el libro]" because the book is a thing. However, I also say "lo vi [a él]" when I see a man. So, why do we say "le hablé [a él]" instead of "lo hablé [a él]"?

Another example, "les mando besos [a ellos]", but not "los mando besos [a ellos]". Why?
And, it's "La conocí [a ella]", not "Le conocí [a ella]".

At first, I understood I should use "le" and "les" when I'm talking about a person and "lo", "los", "la", "las" for things. Now I see it's not like that. Are there any rules, or are these exceptions?

Thanks,

Troy

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Dear Troy,

I hope I'll be able to explain this to you. The key is to recognize if it's a direct or an indirect object. You see, "le" is an indirect object pronoun and "lo" is a direct object pronoun. So, let's take a quick look on direct/indirect objects...

Direct object: a noun phrase denoting a person or thing that is the recipient of the action of a transitive verb. You may find the direct object by asking "who?" or "what?" is receiving the action.

Indirect object: a noun phrase referring to someone or something that is affected by the action of a transitive verb (typically as a recipient), but is not the primary object. You may find the direct object by asking "to whom?" or "to what?".

For example: "Juan da un regalo a María." (John gives Mary a present)
The direct object is "un regalo", because the present is what it's being given. The indirect object is "María", because the gift is being given to Mary.

So, you can say "Juan le da un regalo"
("le" substitutes the indirect object --> to Mary)
And also "Juan lo da a María"
("lo" substitutes the direct object --> the gift)

Note that the direct object NEVER uses a preposition, whereas the indirect object USUALLY uses a preposition (in the proper structure) but it's not required always.

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Now, let's check your examples:

In "lo tiré [el libro]", "lo" substitutes the direct object --> the book (what is being thrown)

In "lo vi [a él]", "lo" substitutes the direct object --> him (who is being seen). The "a" in "a él" is the personal "a" and is not marking "él" as an indirect object. The direct object pronoun "lo" is therefore used.

In "le hablé [a él]", "le" substitutes the indirect object --> to him (I spoke to him). To whom are you speaking? Him. "Him" is therefore an indirect object and the indirect object pronoun "le" is used.
Compare this with "I spoke English". What are you speaking? English. Here "English" is a direct object.

In "les mando besos [a ellos]", "les" substitutes the indirect object --> to them (I send them kisses. i.e. I send kisses to them

Finally, you say "La conocí [a ella]", because "la" is the feminine direct object pronoun. In this case, "ella" is the direct object pronoun. Again, don't confuse "a ella" with an indirect object. Maybe it's easier if you think in English:

To meet him (Conocerlo) --> Who is being met? Him.
To know her (Conocerla) --> Who is being met? Her.

But don't think in English all the time! This is just to show you an example so you can understand better the verb "conocer".

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Please, take note that in some Spanish speaking countries people use "le" as a direct object pronoun instead of "la" and "lo". According to the RAE (Royal Spanish Academy) this is incorrect. This is known as "leísmo".

If your Spanish level is high, you may also want to check the RAE's Diccionario Panhispánico de Dudas. It's the best reference, but if your Spanish level is intermediate or you're a beginner, try visiting StudySpanish.com.

Take care,

- Karin