Public speaking is as old as civilisation. It was elevated to an artform by the orators of ancient Greece, polished into propaganda by the Senators of Rome, and has been used and abused by countless silver-tongued speakers in the centuries since, from Lincoln to Hitler.
The point is, whatever you want to say in your speech, it's highly likely that somebody more famous and clever than you said it first. Careful use of literary, historical or contemporary quotations can add much to your best man's speech, bringing insight, humour or a touch of class. It's not hard to avoid cliché, as your options are almost limitless.
As Best Man, you need to keep the crowd smiling. Fortunately, comedians and writers have been riffing on the perils and pleasures of marriage for centuries, giving you a rich well of observation to draw from. Some of these you might be tempted to pass off as your own, but why not acknowledge the source in your speech? A great joke works whoever wrote it, and it's your delivery they'll remember. Here are a handful of classic lines:
"My advice to you is to get married. If you find a good wife, you'll be happy; if not, you'll become a philosopher." - Socrates
"I was married by a judge. I should have asked for a jury." - Groucho Marx
"Marriage is neither Heaven nor Hell, it is simply Purgatory." - Abraham Lincoln
"Some women pick men to marry, and others pick men to pieces." - Mae West
"A man is incomplete until he's married. After that, he's finished." - Zsa Zsa Gabor
"The man who says his wife can't take a joke forgets that she took him." - Oscar Wilde
"Before we got married, my wife and I both made a list of five people we could sleep with. She read hers out and there were no surprises … 1: George Clooney, 2: Brad Pitt … etc. I got the better deal. 1: Your sister." - Michael McIntyre
Having sold you on the virtue of using quotations, a special word about poetry, which is much tougher to tackle than a witty one-liner …
Ever since John Hannah blubbed his way through that Auden poem about stopped clocks and juicy bones in Four Weddings & A Funeral, it's been the done thing for someone or other to wheel out a bit of verse every time there's a family function. Oldest boy off to uni? "And - which is more - you'll be a man, my son!" Uncle Eric popped his clogs? "'Tis better to have loved and lost …"
The trouble is, there's limited number of very well known poems that fit the theme of weddings to a tee. Yes, you'd be hard pressed to find a better account of the promise of early marriage than Shakespeare's Sonnet 116. And if you're Scottish, it might be genetically impossible to resist the pull of Rabbie Burns' tender masterpiece, "O My Luve's Like A Red, Red Rose". But don't expect to surprise anybody with such well trodden ground. These poem's pop up more often than toast in a fat girl's kitchen.
Moreover, if you are only a casual reader of poetry, you will find delivering it aloud in a convincing manner more trying than almost anything else you could put in your speech; it will certainly require more practice if you're to avoid sounding like a reluctant schoolboy at the front of class.
If the bride and groom have a verse that's particularly significant to them personally, do the right thing, bite the bullet and get practicing. And if you do choose to include a poem yourself, familiarise yourself with its spoken rhythm by rehearsing it aloud, and make sure that you absolutely understand what it's saying, or the impact will be lost.