What did Thoreau mean in the "treason" passage from "A Plea for Captain John Brown"?

Question

In A Plea for Captain John Brown, Thoreau writes:

Treason! Where does such treason take its rise? I cannot help thinking of you as you deserve, ye governments. Can you dry up the fountains of thought? High treason, when it is resistance to tyranny here below, has its origin in, and is first committed by, the power that makes and forever recreates man. When you have caught and hung all these human rebels, you have accomplished nothing but your own guilt, for you have not struck at the fountain head. You presume to contend with a foe against whom West Point cadets and rifled cannon point not. Can all the art of the cannon-founder tempt matter to turn against its maker? Is the form in which the founder thinks he casts it more essential than the constitution of it and of himself?

Of what matter does Thoreau speak here? Does the author compare the cannon-founder, their art of casting cannons, the form and the constitution of their casts to anything?

Answer 1

To summarize the passage: the government that labels John Brown's actions as "treason" is, in Thoreau's opinion, setting itself in opposition to God.

The key section is this:

High treason, when it is resistance to tyranny here below, has its origin in, and is first committed by, the power that makes and forever recreates man.

The ”power” Thoreau refers to is God. In other words, God opposes the tyranny of slavery, and inspires human beings (like John Brown) to do the same.

The remainder of the passage describes the futility of trying to fight God:

When you have caught and hung all these human rebels, you have accomplished nothing but your own guilt, for you have not struck at the fountain head.

The "human rebels" are God's agents; God remains untouched.

You presume to contend with a foe against whom West Point cadets and rifled cannon point not.

You can't point a gun at God.

Can all the art of the cannon-founder tempt matter to turn against its maker?

Here we get into the section that you were most concerned about.

"Founder", in this context, means someone who melts metal and pours it into a mold or cast.

By “matter”, Thoreau means...matter. Stuff. That which has physical existence. Not-energy.

Thoreau's point is that all matter belongs to God, because He made it; it is His in the most fundamental sense. Humans can turn matter or raw materials into a cannon, but they can't turn it against God Himself, no matter how skilled they are.

Is the form in which the founder thinks he casts it more essential than the constitution of it and of himself?

The same point again; the "constitution" of the cannon—that is, the stuff it is made up of—is more "essential" than the human-made shape of the cannon. Thoreau extends his point by noting that the human making the cannon is also made up of God-created matter (“the constitution...of himself”).