The Bible: He wrote it - we quote it! Why quote others?
Bees gather honey from a lot of flowers so speakers need to gather nectar from a lot of sources
If you havent struck oil in the first three minutes, stop boring George Jessel
The man who never reads will never be read; he who never quotes will never be quoted. He who will not use the thoughts of other mens brains, proves that he has no brains of his own Charles Spurgeon