cast down = set or placed. The seats of Orientals are cushions laid, not "set", but "cast down". The reference is to this, in Rev_4:2. Compare Psa_9:7; Psa_29:10. Isa_28:6.
the Ancient of days = the Everlasting One. Compare Psa_90:2. Rev_4:2.
did sit = took His seat.
white as snow, &c. Compare Rev_1:4.
his wheels = the wheels thereof: i.e. of the throne. Compare Eze_1:15-20, Eze_1:26-28; Eze_10:9-13.