This hook sentence creates a suggestion or advice regarding your essay’s main idea / topic / theme.
Example
If you are writing an essay arguing what makes Santiago a great role model in The Old Man and the Sea, you could use this:
“People should have role models since they provide inspiration, motivation and guidance that provide a person with a standard to strive towards.”
This hook sentence lets the reader know the importance of role models and how they can benefit a person. The reader will probably agree with this statement and now be more easily persuaded by your essay arguments.