It depends on whether the writer is famous or the celebrity is famous. Usually, if the former is famous and influential at that time and later generations, then the famous words in the book are his, such as Confucius' famous words, which we are all familiar with and recorded by his students, but we will all say what Confucius said at that time. However, in another case, the writer is not famous or famous, but the famous person who eulogizes it is famous, then this famous saying will be considered as said by the famous person who eulogizes it.