A good way to look at the First Amendment is to think of it as the people's right to hear, enforced by the person best able to know that the people are not being allowed to hear.

In certain areas of the law, people are empowered to bring lawsuits for the benefit of the public because those people are in a position to know of the offense. For example, one can bring a so-called "qui tam" action for Medicare fraud that the complainant has witnessed, even if the complainant hasn't suffered any special loss from the fraud. In such cases, the complainant is a "private attorney general," a whistle-blower, who gets a cut of the government's damages for bringing the suit.

While we like to think of free expression as our right, the right to give a speech to an empty room is of no importance to our organic law. It might be a good idea to allow such speeches, but the survival of the Republic does not depend on them. Only the speeches that can be heard matter, which is why suppressing free speech is an offense against the audience, not against the speaker, and anyone claiming a constitutional right to speak is, in effect, acting as a private attorney general on behalf of the public that is being denied access to the speaker's arguments.

The point of this change in emphasis is that Constitutionally protected free speech is not about the search for truth; it is about the publication of political positions. I want to know that anti-Semites feel strongly enough about their bigotry to publish and to march. How am I to know what people want unless the law permits them to argue for it? I don't want to hear their arguments, but I want to know that their arguments are being made. That is the essence of the First Amendment's protection of free speech (and assembly, where speeches can be heard).

James Madison is "the man" on this issue:

"In Madison’s view, a free republic depends ultimately upon public opinion. A Constitution could divide power this way and that, but in the end it is the people, and only the people, who rule. And for the people to rule wisely, they have to be able to communicate with one another — freely, without fear of reprisal. Thus, freedom of speech and press were not, for Madison, merely God-given rights. They were preconditions for self-government."