Merkabah, Hebrew for chariot, names the mysticism built on Ezekiel 1 and 10: the wheels (ofanim), the living creatures (hayyot), the sapphire throne. The Hekhalot literature (c. 2nd-7th centuries) records ascent practices through heavenly palaces to the throne, guarded by angels, with hymns as passwords.
The modern reinterpretation: Merkaba as a counter-rotating star tetrahedron light-body, activated by breathwork, a 1980s-90s channeling product (Drunvalo Melchizedek's Flower of Life program) that shares the ancient word and little else.
What the two versions share: ascent requires passwords, stages, and peril, the heavenly bureaucracy admits the prepared. Whether palace or light-body, the Merkabah model insists the upper worlds have security, and the mystic's job is credentials.
Is the chariot a vision to be interpreted, or a vehicle to be operated?