"As Mark Twain said: 'The difference between the right word and the almost right word is the difference between lightning and the lightning bug.'"

So starts my husband's edition of Roget's Thesaurus of Words and Phrases copyright 1947. He bought it as a college textbook in 1969 for $2.95. There are several different prefaces in this edition, the oldest being the Preface to the First Edition (1852) when Peter Mark Roget published his 'system of verbal classification' that he first came out with in 1805. A later edition, 1879, was published by the son, John L. Roget, and the 1925 edition by HIS son, Samuel Romilly Roget.

The edition I have here is The Authorized American Edition, edited by Willard Jerome Heggen with the sanction and approval of Samuel R. Roget, the original author's grandson.

Here is how it works, quoting:
"1. Look up in the index in the back of the book the word for which you want a substitute.
2. Note the category number of the group which seems to fit your needs best.
3. Turn back to this number which you will find at the top of the page in the main part of the book. And there you will find the right word, the exact word for your purpose."

To me, this seems the most intuitive, obvious use of such a book, not too different from the way a person would use a dictionary for the same purpose. But the 'main part' of Roget Thesaurus goes further by creating classifications of concepts.

Here are some of the Classes with subclass examples:
-- Abstract Relations: Exisence: Abstract, Concrete, Formal, Modal
-- Time: Absolute; Relative (1. to succession; 2. to a period; 3. to an effect or purpose); Recurrent
-- Matter: Inorganic Matter: Solids; Fluids (1. In General 2. Specific 3. In motion)
-- Volition Division I: Individual Volition (Acts, Subservience to End, Precursory measures).

The words to do with "in motion" are: stream, wind, conduit, air-pipe. I like "imperfect fluids: semiliquidity, pulpiness, bubble, unctuousness, oil, resin.

Now, these are all just headings. There are tons of words under each of them, some of which I've never heard, so a cursory perusal of this fine book turns into an afternoon's amble through the dictionary.

Of course today we have the Internet with free sites like thesaurus.com , and it is easier to jump from one idea to another, but there is something special about holding the book and leafing through the printed word.