Seeing many things, but, etc. Israel had "seen many things;" i.e. passed through a long experience, but not profited by it—not been "observant," as they should have been. They had had their ears open in a certain sense, and heard the words that the prophets addressed to them, but had not taken in their true import.
(The mixture of persons is like that in Isaiah 1:29 and Isaiah 14:30.