Jennings is well known for his participation in the Rosicrucian revival of the late 19th century, which is epitomized in his work, The Rosicrucians, Their Rites and Mysteries (1870). According to Sabazius (2004), this book proposes that the primitive worship of Light or Fire, symbolized by the sun or the phallus, is the true origin of all religions.
Jennings's other works include:
- Indian Religions, or Results of the Mysterious Buddhism (1858)
- Curious Things of the Outside World: Last Fire (1861)
- Live Lights and Dead Lights (1873), One of the Thirty, a Strange History (1873)
- The Obelisk: Notices of the Origin, Purpose and History of Obelisks (1877)
- Childishness and Brutality of the Time (1883)
- Phallicism, Celestial and Terrestrial, Heathen and Christian (1884)
- Charon: Sermons from the Styx: a Posthumous Work by Frederick the Great (1886).
- Sabazius. (1997). Hargrave Jennings (http://www.hermetic.com/sabazius/jennings.htm). Retrieved on Sept. 21, 2004.
- Wikipedia. (2004). Hargrave Jennings (http://en.wikipedia.org/wiki/Hargrave_Jennings). Retrieved on Sept. 21, 2004.