I have shewed thee new things— The new things refer to the prophesies respecting the deliverance of the Jewish people by Cyrus, and the consequence of that deliverance. They are created now, says the prophet, speaking of the first revelation of these things. The idea is elegant; for what is revealed exists by the word which proceeds from the mouth of God; which is the character of creation. The next words may be rendered, And not from the beginning, nor before this day, hast thou heard them.
See commentary on Isaiah 48:3