How did Oliver Wendell Holmes, Jr. explain the limits on freedom of speech?

Oliver Wendell Holmes, Jr. explained the limits of freedom of speech through the legal standard of "clear and present danger."12

In his opinion for the U.S. Supreme Court in Schenck v. United States (1919), Holmes argued that speech otherwise protected by the First Amendment may be prohibited if it is of such a nature and used in such circumstances that it creates a clear and present danger of bringing about substantive evils that Congress has a right to prevent.1

Holmes famously illustrated this limitation with the example that the most stringent protection of free speech would not protect a person from falsely shouting "fire" in a theater and causing a panic. He maintained that while the Constitution protects the freedom of thought—even for ideas that are hated—this protection does not extend to speech that poses an immediate threat to public safety or order.2