Really it depends upon what the author makes it. If it's a published book, it's a for entertaining purposes. If it was informal, it's be a biography.
<span>Keats used it in one instance, where he was criticising Coleridge, who, in the opinion of Keats, wrote his poetry in order to search for truth and as a result missed out on beauty and its elevating affects. </span>I hope my answer has come to your help. God bless and have a nice day ahead!