Learn English – Should we use ‘the’ every time when writing about a specific thing

If you want to look at an example of this, I suggest looking up Aesop's fables. They are relatively short, are easy to find online for free, and most of them feature animals as the characters. Throughout the story, each animal is referred to as "the [animal]" numerous times, and it sounds natural. If the animal is described using "a/an" the first time, this becomes "the" for all of the subsequent references, assuming that the story is referring to that same individual (not a different individual of the same species of animal).

For an example, you can refer to the story of "The Tortoise and the Hare" at this link: http://read.gov/aesop/025.html. The first reference to the hare is "A hare," indicating that this animal is new to the reader and has not been described previously. All later references to the hare use "the hare." For the tortoise, the first reference calls him "the tortoise," and so do all later references. To me this might mean that the tortoise has already appeared in another story earlier in this collection, such that the reader would know this is "the" tortoise, meaning the same one that we are familiar with from an earlier story in this book. If the author wrote "A tortoise" in the middle of this story, it would give the impression that this was a new, second tortoise being introduced in the story. And if the author had written just "Hare" or "Tortoise" without "a" or "the," it would sound like that was that individual's name. It's like the difference between saying, "A man walked down the street" versus "Joseph walked down the street." Saying simply "Man walked down the street" would not be correct unless the person's name were "Man," which is possible but not likely. (I once had a terrible, awful, dreadful boss whose first name was "Man," so you never know...)