Answer:
literary 
Explanation:
The definition of literary device is a technique a writer uses to produce a special effect in their writing. 
 
        
             
        
        
        
I believe the correct answer is naive.
The author is trying to say that he was ignorant, and that he couldn't understand properly these new revelations. He was either too young or too stupid to understand such a thing, but he believes he will as he grows older.