根据弗拉纳根，“‘旧的神秘主义者’是二元论者，认为意识不能被科学理解，是因为它根据非自然的原则运行，可以是可知的，也可以是不可知的。”显然，“旧的神秘主义者”适用于戈特弗里德·莱布尼茨、塞缪尔·约翰逊、托马斯·亨利·赫胥黎等人。例如，赫胥黎在The Elements of Physiology and Hygiene[4]和《论动物是机械的假设，及其历史》（见下》中写道：
The consciousness of brutes would appear to be related to the mechanism of their body simply as collateral product of its working, and to be completely without any power of modifying that working, as the steam-whistle which accompanies the work of a locomotive engine is without influence upon its machinery. Their volition, if they have any, is an emotion indicative of physical changes, not a cause of such changes... The soul stands to the body as the bell of a clock to the works, and consciousness answers to the sound which the bell gives out when it is struck... To the best of my judgment, the argumentation which applies to brutes holds good of men... We are conscious automata.[2] — 托马斯·亨利·赫胥黎， "On the Hypothesis that Animals are Automata, and its History"， 1874
McGinn, Colin (1993), Problems in Philosophy: The Limits of Inquiry, Blackwell, ISBN1-55786-475-6
Horgan, John (1996), The End of Science: Facing the Limits of Knowledge in the Twilight of the Scientific Age, Addison-Wesley; has a discussion of mysterianism (pp 177–180).
