"Had I Not Been a Philosopher, a Man of Cool, Calm Reasoning, I Should Have Killed Him There and Then"

"The Glen Echo Mystery."
By Walter Wellman (1858-1931).
First appearance: The Black Cat, December 1898.
Reprinted in The Black Cat, December 1908 and Detective Book Magazine, July 1931.
Short story (14 pages).
Online at SFFAudio HERE (PDF).

"It was necessary that everything should be done in a prudent and orderly way."

Mr. Sylvester Baldwin is spending a fortnight with his friend and classmate at Harvard, Prof. Edwin Stone, at the latter's home when just after a house party given in his honor Baldwin inexplicably goes missing:

From that moment not the slightest trace of the young lawyer has been secured. The last known of him, he was apparently lying in bed, reading, a happy man. Next morning he was not in his room. All his clothing and effects, save only the pajamas which he wore as a night robe, were in the apartment. He had disap-peared as completely as if the earth had swallowed him up.

A thorough search—and we do mean thorough—is initiated by a squadron of police detectives, but:

They found not the slightest trace of the missing man, dead or alive.

In due course our narrator will tell us why Sylvester Baldwin has disappeared and, just as importantly, the life-and-death significance of a locket containing the portrait of a lovely young woman.

Note: This appears to be the only "mystery" that our author ever had published.

The bottom line: "Jealousy contains more of self-love than of love."
— Francois de La Rochefoucauld