So, some things (I think) I already understand:

• 'Gothic' as a term that describes things associated with the Goths: the eastern Germanic tribe that was a major force during the Roman Empire up to the 'Middle Ages'.

• 'Gothic' art and architecture. A stylistic movement prevalent from the 12th through the 15th centuries in central Europe. I understand how an art and architectural style that evolved in the areas that were traditionally home to the Goths would be called 'Gothic'.

I get lost when we make the transition into 'Gothic' literature (and thus: Gothic themes). When I looked it up, I discovered that the first use of 'Gothic' as a literary term was the sub-title to the novel The Castle of Otranto: A Gothic Story. But I have no idea why Horace Walpole decided to subtitle his novel "A Gothic Story". The titular castle is located in Apulia, Italy (the heel of the boot), which is just about as far from Gothic Europe as you can get and still remain 'European'.

Is the novel 'Gothic' because it came about at a time when 'Gothic' was the prevalent artistic and aesthetic movement? There's some debate as to whether Walpole's novel is simply a translation of a story that came about during The Crusades, which would put it somewhere in the Gothic period. Was Walpole, with his subtitle, referring to the time period in which the story was set, during which 'Gothic' was the predominant aesthetic?

I understand how Walpole's themes became representative of the dark and macabre themes that we, today, associate with Goth and Gothic. But I don't understand how we went from a tribe and a central European artistic and architectural aesthetic to a literary aesthetic.