No no no! The thesaurus is the work of the devil. The basic organizing principle is that there are clumps of words that all mean the same damn thing. In fact there are few or no words in English that mean exactly the same thing. Using a thesaurus to write with leads to a paper full of strangely misused words--what we in the humanities call "the thesaurus syndrome" and recognize in an instant.
The way to enlarge your vocabulary is to read widely. There may be shortcuts, but a thesaurus is not one of them.
I realize Larry's response is four years old, and that in the interim he may have seen the light and changed his ways, but just in case, I have to agree with namazu and infopri that the thesaurus is only the work of the devil when in the hands of nimrods.
The time when the thesaurus is most useful to me is the time at which I know I haven't used *quite* the word I wanted -- when I know that there exists an alternative that more precisely expresses what I want, but which at that particular moment eludes my mnemonic grasp. In other words, it is useful for reviewing the various shades of meaning of
words I already know, not for randomly choosing to replace one word with a word I don't recognize that has more syllables or fancier letters (preferably ones that include umlauts) than the original.
Also, thesaurus.com has a nice feature nowadays in which they show you via diagram the general spheres of meaning to which a word is connected and how it relates to other words which share that particular connotation. It's very interesting.
VP
