I have declared the former things from the beginning; and they went forth out of my mouth, and I shewed them; I did them suddenly, and they came to pass.
I have declared the former things - things which have happened in time past to Israel (Isaiah 42:9; Isaiah 44:7-8; Isaiah 45:21; Isaiah 46:10).
I did (them) suddenly, and they came to pass - they came to pass so unexpectedly that the prophecy could not have resulted from mere human sagacity.