Here is another good reason to read not just the law, but literature, history, etc. Reading is a time honored method of improving vocabulary. This article "The Art of Written Persuasion: Part V - Improve Your Vocabulary, Improve Your Success" is a discussion of what is meant by "good vocabulary" - it is more than big words - and describes how lawyers use vocabulary to persuade.
It is not a long article and is a fine explanation of why lawyers need a good vocabulary.
Ernster, the Virtual Library Cat
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