Madness imagery
Many characters in Lovecraft's short stories suffer mental breakdowns or go insane because of the horrors they experience. In "Beyond the Wall of Sleep" the narrator describes a psychopath who, after having dreams of extraterrestrial, light-based beings, loses his grip on sanity and becomes violent. Some of his stories are prefaced by a narrator's claim that, because of his own mental health issues or impending death, the stories may be difficult to believe. In "The Temple", crewmen on a U-boat become delirious and mutiny. In "The Tomb", a man gradually comes to believe that he is the reincarnation of somebody else, and dreams that he is sleeping inside a mausoleum although other people observe him sleeping outside it. Although the delusions suffered by Lovecraftian characters appear to be the results of mental disturbances, in each story the "mad" or delusional character is the only one who is right and who has a full grasp of the facts.
Transformation imagery
Several of Lovecraft's short stories feature a character or beast that turns out to be a transformed human being. In "The Beast in the Cave", there is a creature prowling Mammoth Cave that turns out to be a human being who, lost in the cave long ago, developed adaptations that allowed him to survive in the cave environment. Likewise, in "Memory" two supernatural beings debate the origin of some of the phenomena around them, and conclude that the human race has degenerated into a group of ape-like beings.
Dream imagery
Disturbing dreams are a hallmark of the chaos and madness induced by the otherworldly beings of the Cthulhu mythos and by the interaction between characters and unseen extraterrestrial or extra-dimensional entities. In "Nyarlathotep", the entity that takes on the form of a traveling showman or conjurer induces strange, disturbing or horrifying dreams in those who observe his performances or interact with them. The critical insight in "Beyond the Wall of Sleep" comes when a doctor attempts to initiate telepathic contact with a psychopath who describes strange visions that occur during his dreams. In "The Tomb", the main character's growing awareness that he is the reincarnation of a different man is due to the insights he receives while he dreams.
Ocean imagery
Lovecraft uses the ocean, which is a convenient dark, unknown, and threatening place, as a good way to hide monsters and secrets. Like the much more famous "The Call of Cthulhu" (which does not appear in this book), "Dagon" features an encounter between a mariner and an unspeakable horror that is rising from the sea after a long period of dormancy. "The Temple" features an underwater exploration in which a submarine captain explores what appears to be a submerged Atlantean temple. Philip Jermyn disappears mysteriously at sea, and the eponymous "Terrible Old Man" has a nautical history.
Science imagery
Many characters in Lovecraftian fiction are men of science who invent machines that pierce the fabric of reality and that allow communication with, or actual travel between, unknown and frightening dimensions. In "Beyond the Wall of Sleep" the device that allows a medical researcher to experience the vivid dreams and hallucinations of a psychopath is the means by which the researcher becomes aware of the beings of light that caused the psychopath's mental collapse. In "From Beyond", Crawford Tillinghast invents a device that generates a special kind of electromatic wave that affects the pineal gland of an experimental subject, allowing that person to perceive and interact with entities in other dimensions of reality. Finally, in "The Temple", a submarine and a sophisticated diving and underwater exploration apparatus allow a man to explore what appears to be an underwater temple.
