Using Definite Articles

After studying Spanish for as long as I have, I can't believe I still have such a basic question, but so be it...

Spanish uses definite articles much more than we do in English, such as this phrase from lesson 15.4:

“Y mi palabra es la ley.”
"And my word is law."

Another example (my own construction):

"I began the flash cards for lesson 15.4"
"Comencé las tarjetas de memoria por la lección 15.4"


The use of definite articles seems a bit inconsistent and arbitrary in sentences such as these. It seems that, most times, using the definite article is correct even when not used in the corresponding English sentence, but other times it is not used in a sentence of the same basic construction.

Has anyone else encountered this inconsistency, or am I missing a basic rule of Spanish grammar here? Or is truly optional and either construction is correct?



 

Dan,
       I would say that both are correct, at least in conversational terms. Honestly, I would see the direct translation of the first sentence into English as "And my word is the law" because if standing alone "la ley" is "the law." And in the second sentence, one would think the direct translation into English would be "I began the flash cards for the lesson 15.4." Perhaps the seemingly "extra" articles are simply added for a certain amount of emphasis and clarity.

When and when not to use the definite articles is something I have struggles with also.  When in doubt I always use them.  However, it seems that when the noun is characteristic or one in nature with the subject then it doesn't need the article such as the following:  "Dios es luz" o "Dios es amor."

​This is just my observation and may or may not have any real value.  :)

Indeed. I just came across an example where I would have definitely put in an article:
- And, to tell you the truth...    Y, a decir verdad...    

I think there are cases where it's just the way you say it (like a formula) and that adds to the confusion. I've been finding out though from people learning English that these kinds of things are much more complicated for them!