The first three chapters of Isaiah provide an overview of the first 39 chapters of the overall book. In these three chapters we discover the charge against Judah (the southern part of the nation of Israel). Isaiah asserts that Israel is dumber than an ass and ox - they at least know their master, Israel does not.
Isaiah pleads with them to "wash yourselves clean" - "devote yourselves to justice" by "aiding the wronged, upholding the rights of the orphan, defending the cause of the widow".
Their guilt was not just based on evil thoughts or motives, but on actual neglect of those in need and actual hoarding of power, privilege and wealth for themselves at the expense of others. To those that oppress the poor, they oppose God; and He will "wreak vengeance on My enemies!". He says that "repentant ones will be saved, but rebels and sinners shall all be crushed".
According to the Isaiah, there is a direct connection between oppression and neglect towards widows and orphans and the failure to study, understand, and apply God's Instructions. Also conncted to this failure is a preoccupation with possessions and pleasing powerful people at the expense of enjoying God and his gifts.
I was moved by this phrase:
"Oh, cease to glorify man,
Who has only a breath in his nostrils!
For by what does he merit esteem?
And this phrase:
"The Lord stands up to plead a cause,
He rises to champion His people
How dare you crush My people
And grind the faces of the poor?
What will God do to crushers and grinders?
He will bring them an opportunity to repent, and then for the proud he will bring them justice.
Do your purchasing habits, your leisure habits, your consumption habits, your work habits result in the crushing or grinding of others?
Does your life give life to others, or does your life require the crushing of another?
Isaiah seems to be addressing both those that intentionally crush and grind, as well as those that are ignorant and oblivious. His point is that God wants the grinding and crushing to cease. God wants shalom/peace to be the possession of all men and women in all lands - and he wants His people to be more preoccupied with spreading peace then protecting/accumulating possessions and prestige.