Final answer:
Holmes meant that during wartime, certain speech or expressions that would be tolerated in peacetime can be punished.
Step-by-step explanation:
Holmes meant that during wartime, certain speech or expressions that would be tolerated in peacetime can be punished. This is because the government has a right to prevent words or actions that may cause harm or jeopardize the nation's security.
Holmes used the example of shouting 'fire!' in a crowded theater, which is not protected by the First Amendment because it poses a clear and present danger. Similarly, during wartime, speech that would promote violence against the government or hinder the war effort can be restricted to protect the country.