Historiography is one of the most useful parts of an essay which you can use as it furthers, or limits, the argument which you have presented. It is used when you have presented all of your evidence for your point. This is when you corroborate your argument with the opinion of a scholar to prove the value of your point. You may also choose to use historiography to limit your point as this shows that you understand the argument in great depth. After doing this, babe sure to rebut the historian's claim and show why your argument is stronger.