Read the following passage and answer the (two) items that follow:
A book is written, not to multiply the voice merely, not to carry it merely but to perpetuate it. The author has something to say which he perceives to be true and useful or helpfully beautiful. So far he knows no one has said it, so far as he knows no one else can say it. He is bound to say it clearly and melodiously if he may; clearly at all events. In the sum of his life, he finds this to be the thing or group of things, manifest him; this the piece of true knowledge or sight, which his share or sunshine and earth has permitted him to seize. That is a book.
According to the author, a person is implied to write a book because-