Spiritual hyperplane - spiritualists of the 19th century

https://aeon.co/essays/the-occult-roots-of-higher-dimensional-research-in-physics?utm_source=Aeon+Newsletter&utm_campaign=58cf527a96-EMAIL_CAMPAIGN_2018_01_15&utm_medium=email&utm_term=0_411a82e59d-58cf527a96-69623653