Dictionary~Thesaurus

     Recently, I adjusted the stance of my hardbound reference books––Roget's Thesaurus, Rodale's The Synonym Finder, Webster's New Collegiate Dictionary, and The Chicago Manual of Style––which listed precariously close to the shelf's edge, despite a weighted bookend. Straightened in their place of honor, they are again easy to reach from my desk chair when I write.
     The dictionary and thesaurus are the most frequently retrieved of the above group, and they show the grasped use with chiseled edges, re-glued alpha tabs, and spines working loose. I thought about the role of these two volumes as I made order on that shelf. I wondered if one had become more important than the other, and if so for what reason? To find out, I made a list of what each book contributed to my writing endeavors. I share my findings with you.

DICTIONARY

• provides an alphabetical list of words with definitions, parts of speech, phonetic pronunciations, and etymologies;
• you start with a word and look for its meaning
• its purpose is to define and pronounce words
• precise words provide articulation to your written voice

THESAURUS*

• a book of words grouped by ideas
• you start with an idea and find the words to express it
• look up the idea word in the index, and find beneath it the closest synonym
• turn to the numbered section you choose from the index to find synonyms, suitable antonyms, phrases, and expressions
• provides parts of speech

* the plural of thesaurus is "thesauri" or "thesauruses;" its adjective is "thesaural"

     About the time I was pondering the merits of each of these two volumes, another of John McPhee's articles in his Writing Life series (Draft No. 4) appeared in the April 29, 2013, issue of The New Yorker. I provide a portion of it below, but please note underlines are mine.

You draw a box not only around any word that does not seem quite right but also around words that fulfill their assignment but seem to present an opportunity. While the word inside the box may be perfectly O.K., there likely to be an even better word for this situation, a word right smack on the button, and why don't you try to find such a word? If none occurs, don't linger; keep reading and drawing boxes, and later revisit them one by one. If there's a box around "sensitive," because it seems pretentious in the context, try "susceptible." Why "susceptible"? Because you looked up "sensitive" in the dictionary and it said "highly susceptible." With dictionaries, I spend a great deal more time looking up words I know than words I have never heard of––at least ninety-nine to one. The dictionary definitions of words you are trying to replace are far more likely to help you than a scattershot wad from a thesaurus. If you use the dictionary after the thesaurus, the thesaurus will not hurt you.

I summarize my list, and feel somewhat blessed by Mr. McPhee's remarks:

• I reach for the dictionary first to be sure the word I've chosen fulfills the definition of my intent. This is the book that presents (for me) the best choice of words.
• After that, the thesaurus comes to desktop for 1) finding a more nuanced word, and 2) to avoid the repetitive use of a particular word. But even then, I will go back to the dictionary to verify that the new word is suitable.
• I use the two books hand-in-hand to be sure I convey the right word for the right context and prevent confusion. 
• In the revision process, the thesaurus works overtime, allowing my writing to have more variety or wordplay, but only when I'm careful.

Do you prefer one word reference book over another? Is it easily at hand? 
I'm curious to know how other writers perceive their dictionaries and thesauri, and why?