Yost began visiting Pearl Curran around 1914. Curran, a St. Louis housewife, claimed to be channeling via a Ouija board, and entity calling herself Patience Worth. Yost wrote a series of articles for his paper on ‘Patience’ and in 1916 he published his book, Patience Worth: A Psychic Mystery.

He wrote in the foreword:

The editor of this book is not a spiritualist, nor a psychologist, nor a member of the Society for Psychical Research; nor has he ever had anything more than a transitory and skeptical interest in psychic phenomena of any character. He is a newspaper man whose privilege and pleasure it is to present the facts in relation to some phenomena which he does not attempt to classify nor to explain, but which are virtually without precedent in the record of occult manifestations. The mystery of Patience Worth is one which every reader may endeavor to solve for himself. The sole purpose of this narrative is to give the visible truth, the physical evidence, so to speak, the things that can be seen and that are therefore susceptible of proof by ocular demonstration. In this category are the instruments of communication and the communications themselves, which are described, explained and, in some cases, interpreted, where an effort at interpretation seems to be desirable.

Casper Yost died in St. Louis in 1941.