What does Zion / Jerusalem represent (for me)? It represents the Kingdom of God, the people of God, the person of God. Those who by grace He has chosen and redeemed to be His. Those who are to proclaim the good news of this amazing grace, and charged to be instruments of justice.
At this point, Isaiah has already seen a lot. From being in God’s presence, to seeing pain and suffering caused by sin, to seeing the glory of God’s strong redeeming hand. There’s no turning back from such visions. “I will not keep silent, I will not be quiet.”
Maybe the problem is because we, I, do not see. Or cannot see? Refuse to see? Otherwise I would likewise be – not silent, not quiet.
There will be great days for you Zion. As for me, give me vision Lord…