Entering somewhat unfamiliar territory, to aid some of the symbolic, numerical and yes, clairvoyant topics and contemplations, came across this resource book ref 
Augusta Curtiss  was an original author of many books that one could, I guess, classify as Christian mysticism, but this is far too strict of a classification, this particular book
pertains to the subject of numbers and symbols as it appears in various spiritual and metaphysical (spiritual) texts.
To give you quick taste of the book content, ie she writes:
"Numbers can be compared to bones of the body in that they are framework upon which a superstructure of manifestation is erected"
"In the Bible, from the day of Creation to the Apocalypse, great stress is laid upon numbers , especially 3, 4, 7 and 12"
"The word Tarot maybe written in the form of a cross and read ROTA, a wheel"
The book is packed with various references to spiritual writings from ancient Hebrew texts to the ancient Egyptians, and finds common traits among them.
 - Curtiss, Harriette Augusta - Biography (1856-1932)