While searching for famous quotes to use in your presentation or speech, all that is required to visit Google and there you could find nice quotes for any possible presentation or speech you could ever imagine. You could also choose to go to library and find any book of famous quotations or any good book or quotes. There are plenty of good books. Most of them are categorized by keywords like optimism, success and inspiration etc. Find the quote that relates best to your presentation or speech and use it in the beginning of your speech and possibly to close it.