God has graciously revealed enough that we know He has a wonderful plan, but the details are known by Him alone. They are under His “own power,” or authority. Certainly He knows the future, but more than that, He controls it.
And why not? He created time (Genesis 1:1); surely He can exercise authority over it. Surely the “Alpha and Omega, the beginning and the end, the first and the last” (Revelation 22:13) can control the destinies of individuals and nations. “Power” to work out His good pleasure rests solely with “the only wise God our Saviour . . . now and ever” (Jude 25). [from ICR]