God - in contrast to “the wise men,” etc. (Dan 2:27).
revealeth secrets - (Amo 3:7; Amo 4:13). Compare Gen 41:45, Zaphnath-paaneah, “revealer of secrets,” the title given to Joseph.
the latter days - literally, “in the after days” (Dan 2:29); “hereafter” (Gen 49:1). It refers to the whole future, including the Messianic days, which is the final dispensation (Isa 2:2).
visions of thy head - conceptions formed in the brain.