His main interest was Christian Theosophy; he was influenced by the writings of Jakob Böhme.
[4] Massey, a convinced spiritualist, was associated with the medium Stainton Moses.
He was also a member of the British National Association of Spiritualists and The Ghost Club.
[5][6] Massey had defended the medium Henry Slade against the accusations of fraud from Ray Lankester.
[7] In 1880 he translated Johann Karl Friedrich Zöllner's Transcendental Physics into English.