An essay should be correct. However, to be correct is not enough if it is vague. 

Telling people something novel doesn't always mean surprising them. It could mean telling them something they knew unconsciously but were unable to put into words. In fact, those insights are often more valuable because they are more fundamental.

Many people think a good essay is persuasive. But more importantly, an essay should be useful.
There are four parts to a good essay:

• Write the first draft of an essay fast, trying various ideas. Then spend time rewriting it very carefully.
• If you write a bad sentence, don't publish it. Delete it and do it again.
• If a sentence seems clumsy, ask why it doesn't seem right. By asking thi...

Strength comes from two things: thinking well, and the skillful use of qualification.