The basic theme of “The Diamond Lens” begins to reveal itself only in the last quarter of the story, when the protagonist discovers the beautiful creature in the drop of water under the microscope. It is a typical Romantic theme, predominant in the early part of the nineteenth century and sustained in the century’s closing decades by the influence of Poe’s work on the Aesthetes. “The Diamond Lens” focuses on the difference between the realm of actual, perceptible physical reality and that realm of a more profound reality that is a projection of the human imagination. The issue is the fineness of the perceiving eye, based on the assumption that there is a realm of reality beneath or beyond that of the everyday physical world that partakes of the spiritual and is thus the truest.

The theme is made most clear in the contrast between the figure of Animula and that of an actual female. There is no way that any actual female can compete with the almost spiritual nature of Animula, spiritual because she has a tiny body. The theme is an aesthetic one, in which it is clear that the most human aspiration is to transcend the physical, for the physical is an indication of the grossness of the body itself. The great Romantic ideal is that one responds to a spiritual transcendence of body. The more that body is distanced from the sense of physicality and thus mortality, the more beautiful it is taken to be.

O’Brien inherits this Romantic ideal from Poe’s Platonic retreat from body. The problem of this particular story, however, is that it depends too much on the simple trick ending of the evaporation of the drop of water in which the beautiful creature resides. This event has nothing to do with the theme of the beauty of the spiritual; it is simply a convenient way to indicate the impossibility of the narrator’s love for absolute beauty. “The Diamond Lens,” although it has some of the characteristics of a Romantic fable, is really primarily a trick story appealing to the mid-nineteenth century fascination with trick endings and with scientific fantasies.

“The Diamond Lens,” a scientific fantasy, was very popular in the mid-nineteenth century. This work situates author Fitz-James O’Brien somewhere between Edgar Allan Poe and Ambrose Bierce in the development of such imaginative quasi-scientific fantasies, although O’Brien is not as profound in his use of genre as either of those writers. O’Brien wrote a clever and interesting story about moving beyond the realm of external reality into a world of absolute beauty and mad obsession, a theme that certainly places him in the Poe-Bierce tradition, but “The Diamond Lens” never goes beyond the surface gloss of the slick magazine writing of the time.