<span>The "overachiever" in Frankenstein" by Mary Shelly would definitely be Dr.Frankenstein himself. He brings a man to life scientifically, which kind of makes him an overachiever.</span>
This is a literary technique known as conceit.
A conceit<span> is a kind of metaphor that compares two very different things in a remarkable and smart way. In this poem, the two opposing forces are light and darkness. But still, the author was able to equate them together in a surprising way to relate them both to the theme of beauty.</span>
The term "castle-in-the-air" is actually a term that means something that is imaginary and extravagant and most likely are not realized or carried out. In other words, this is similar to the term "daydream". When we use TV as <span>"castle-in-the-air", the danger for this is that people tend to view something as a reality instead of just accepting it as fantasy. Hope this helps.</span>