What is the origin of the "two-tiered" theory of the First Amendment?

Question

In Chaplinsky v. New Hampshire¹, Justice Frank Murphy says the following:

[I]t is well understood that the right of free speech is not absolute at all times and under all circumstances. There are certain well-defined and narrowly limited classes of speech, the prevention and punishment of which has never been thought to raise any constitutional problem. These include the lewd and obscene, the profane, the libelous, and the insulting or "fighting" words--those which by their very utterance inflict injury or tend to incite an immediate breach of the peace.

The case was on appeal, but Justice Murphy upheld Chaplinsky's arrest.

Two sources I can find says that Murphy is elaborating/advancing the two-tiered theory but doesn't comment on its origin. One², two³

This site which talks about the framers⁴ only references the two-tiered theory in the sidebar under the "categorical" approach name.

If I understand correctly, the two-tiered theory/categorical approach simply refers to exempting certain categories of speech from protection, such as obscenities and "fighting words". However I cannot figure out why the Supreme Court has developed it as the question asked. Some sources like this⁵ and this⁶ both contend that this approach has not been used to uphold a conviction since that one case.

Can anyone help me answer the question?

References:

1. Chaplinsky v. New Hampshire, 315 U.S. 568, 62 S. Ct. 766, 86 L. Ed. 1031 (1942).
2. Chaplinsky v. New Hampshire - Court Develops Two-tiered Theory Of The First Amendment
3. First Amendment Cases
4. Introduction to the Free Speech Clause
5. The Categorical Approach to Protecting Speech in American Constitutional Law
6. Freedom of Speech

Answer 1

There is a PhD dissertation on two-tier theory written by John C. Hughes entitled "John Marshall Harlan, The Warren Court, and the Freedoms of Speech and Press" (July 1978) which has the clue for the origin of the two-tier theory.

In page 219, the author talks about the origin of two-tier theory of free expression and writes that it has been first suggested by Oliver Wendell Holmes Jr. (1841-1935), the Jurist who served the Supreme Court from 1902 to 1932, and later advocated by Robert H. Jackson (1892-1952) who was Attorney General (1940-1941) and serving in the Supreme Court (1941-1954). In the thesis, it has been referred to two sources:

• Page 2804 of the following book: Norman Dorsen, "John Marshall Harlan" in Leon Friedman and Fred L. Israel, The Justice of the United States Supreme Court 1789-1969 v. IV (New York 1969)
• PhD dissertation written by Patricia Ruppert Nelson on John Marshall Harlan: Twentieth Century Federalist (John Hopkins University, 1971), page 18 and the following pages.

Let's not forget that Justice Holmes was for the broad freedom of speech under the First Amendment. I searched more and I found this essay : Safeguarding Speech: The Two-Tiered Amendment at this link: https://bu.digication.com/williamli/Final_Draft in which the author mentions the case Schenck v. United States (1919) as a landmark case where

Justice Holmes argued that the First Amendment applied further than his previously stated prior restraints and established the “clear and present danger” test in which it measured the probability of harm in argued cases (Lewis 26). Most notably, Abrams v. United States (1919) was a turning point when Justice Holmes dissented against the majority opinion which charged four radicals with the Espionage Act, which made it a crime to publish “abusive language” about the Constitution or the armed forces (Lewis 28). Justice Holmes argued against the majority opinion by adding two adjectives to his test: “imminent” and “forthwith” as a better indicator of violation and called the leaflets “poor and puny anonymities,” and that any charge should be “the most nominal punishment” based on their radical views (Lewis 29).

I suggest that this book is a clue and a must-read book to know more about Justice Holmes and the case:
Lewis, Anthony. Freedom for the Thought That We Hate. New York: Basic Books, 2007. Print