In the Light of Truth: The Grail Message was written by Oskar Ernst Bernhardt (1875–1941) and first published in 1926 under the pen name Abdruschin. An expanded, complete edition was published by the author under the name of Abdruschin in 1931, entitled 'Im Lichte der Wahrheit (In the Light of the Truth). It was a collection of 91 lectures, written to build upon each other, presenting a complete picture of Creation. Between 1931 and 1934, a further total of 59 additional lectures were released.