When traveler O'Malley encounters an unusually robust, handsome, and virile man and his equally attractive young son while on a cruise, he becomes strangely enraptured, and is thrilled to learn that the two will be sharing his cabin for the duration of the voyage. O'Malley also notices that when observing the two men from a distance, they seem to oddly amalgamate into one larger being, or, at other times, an immense third presence seems to accompany them. Is it a trick of the light? Is O'Malley a lunatic, hallucinating, or experiencing repressed homosexual desire without realization? Since both father and son rarely speak and communicate largely with their charismatic smiles, pie - eyed O'Malley makes of them what he can and takes them in with his eyes a little more than seems respectable for a presumably heterosexual male: at night, O'Malley goes so far as to pull back the curtains and stare at their undressed bodies while they sleep. In one loaded episode, the father awakens to find O'Malley bending over him and devouring him with his eyes; unperturbed, the father sits up, points to the son, and together they stare at the son's naked chest beautifully rising and falling as the morning light comes up. Since everything suggests that O'Malley is erotically attracted to both men, and the father in some way enamored with his son, their cabin seems more like a blissful, somewhat humid den of unthwarted pedophilia and incest than the place of revelation and miracles Blackwood would like to have the reader believe it is.

Also along for the voyage is the learned Dr. Stahl, who inexplicably has a great understanding of the two strangers and what they threaten. Blackwood allows himself almost a hundred labored and repetitive pages attempting to convey to the reader the secret Dr. Stahl attempts to put into words for O'Malley. The father and the son, as it happens, are not men in the sense that Stahl and O'Malley are men, but are earth spirits, emanations of mother nature, and, as such, two of the last beings of their kind in existence. Blackwood never finds the words to define and describe the two men's metaphysical nature clearly, so Dr. Stahl and O'Malley repeat the same precious discussion over and over, merely approaching it from a slightly different angle each time.

As a struggling, often starving writer, Blackwood was frequently paid by the word, a fact that hasn't been forgotten by his critics. Many of his stories were indeed overwritten, though overwriting was something Blackwood raised almost to an art in many of his short pieces. Unfortunately, his novels, from A Prisoner In Fairyland to The Centaur, were another matter. Had The Centaur been a short story of twenty pages, Blackwood could have conveyed exactly the same information, if, as written, to an equally unconvincing effect. In trying to outline his beliefs about the spiritual aspects of nature, Blackwood abandoned structure entirely and seemed to forget that he was attempting a dramatic narrative. Readers can obtain a much better outline of Blackwood's pantheistic philosophy by reading his short stories than can ever be obtained by reading The Centaur, which is ultimately nothing but a vague, under confident, and winded New Age tract.