Grammar and vocabulary are essentially matters of fashion; they change from generation to generation to some extent. So, writing or speaking according to the fashion of the time is not strictly necessary. However, it is most valuable to be able to express oneself in such a way that those to whom we communicate will have no excuse not to know precisely what we mean. This ability involves the skillful use of vocabulary, syntax and grammar. Further, most people can learn to express themselves adequately in this regard just by reading good writers and paying a little attention as they read. (Of course, no one reads today, and that is the problem.)
Here is an example of poor expression: "Will someone go down to the bus station and pick up a woman there who has a little time to spare?" Obviously, it is not the woman at the bus station who has time, but the person picking her up. Thus, "who has a little time to spare" should be placed after "someone." Just attention to little things like that help make our communication more precise. Also, the use of specific vocabulary helps in that regard. For example, how many more descriptive synonyms are there for the word "walk"? Stroll, saunter, stride, etc. If you want people to know precisely what you mean, then say what you mean precisely.
In this high-tech world, it is also refreshing to read or hear words used beautifully. The ability to turn a phrase in just the right way is an increasingly-rare ability. Consider the skill of Sir Winston in 1940. Had he been an American of today, he likely would have said, "We will be in trouble if we do not win this war." Instead he used loftier phrases, and created something that will last as long as the English language is used:
"Behind them - behind us- behind the Armies and Fleets of Britain and France - gather a group of shattered States and bludgeoned races: the Czechs, the Poles, the Norwegians, the Danes, the Dutch, the Belgians - upon all of whom the long night of barbarism will descend, unbroken even by a star of hope, unless we conquer, as conquer we must; as conquer we shall."
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