[OED:] [2.] a. {intransitive} To deal with some matter in speech or writing; to discourse. (In quot. 1517 transf. of pictorial representation.) Const. of, formerly also on, upon

What are the similarities and differences? Which definition of 'of' fits?
Is of a preposition or a particle?

I encountered this verb phrase below, but notice that the quoted clause with the bold originates from OED's entry on the suffix -logy.

-logy:   word-forming element meaning "a speaking, discourse, treatise, doctrine, theory, science," from Greek -logia (often via French -logie or Medieval Latin -logia), from root of legein "to speak;" thus, "the character or deportment of one who speaks or treats of (a certain subject);" see lecture (n.).

Another example is the title of chapter one of Oliver Twist

Treats of the Place Where Oliver Twist Was Born and of the Circumstances Attending His Birth

  • 2
    Good find. But the questions are specific and different. This asks to compare and contrast treat with treat of, wheras the related question you reference asks about the meaning of treat in context. Mar 31, 2015 at 5:47
  • 3
    "Treat of" is an archaism that survives in some academic prose. books.google.com/ngrams/…
    – TimR
    Mar 31, 2015 at 11:30

3 Answers 3


Both speak and treat (meaning discuss) can be used either with objects (transitively) or without them (intransitively).

One can speak something--speak the truth. It is more common to use speak without an object.

Treat of (something) is relatively less common than treat (something).

Treat of is not a phrasal verb because its meaning can be readily understood in terms of adding denotations of its constituents: treat of = (essentially) talk + about.


Here's a dictionary listing that makes it pretty clear: http://www.thefreedictionary.com/treat

We see that treat of is a special construction that has a special meaning. But it's rarely used now. I don't think I've ever used it in my whole life!

I also speak Spanish, and Spanish has an exact equivalent, which is used frequently -- Este artículo trata de la Guerra Fría (= this article is about the Cold War).

You could distinguish this construction from other ways of using the word treat by associating this with the word treatise ("A systematic, usually extensive written discourse on a subject"). A treatise is long and formal, and treat of is formal.


As another answer noted, Spanish uses a similar construction. It's worth noting that French does so as well, and this is likely the source of the usage in English. "Traiter de" is common, though the verb can also be used alone with the same meaning: https://www.cnrtl.fr/definition/traiter traiter II.A. The construction with de emphasizes the formal, methodical nature of the action.

Ultimately, I suspect both derive from the post-Aug. Latin tracto+de+ablative" construction. This may have been influenced by the more common use of verbs like dissero with de. The French cognate disserter (like the English "dissertate") is synonymous with traiter de in this formal sense and also takes a preposition.

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    Aug 27, 2021 at 15:52
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