More than 2,000 years ago Aristotle outlined a formula on how to become a master of persuasion in his work Rhetoric. To successfully sell your next idea, try using these five rhetorical devices that he identified in your next speech or presentation: The first is egos or “character.” In order for your audience to trust you, start your talk by establishing your credibility. Then, make a logical appeal to reason, or “logos.” Use data, evidence, and facts to support your pitch. The third device, and perhaps the most important, is “pathos,” or emotion. People are moved to action by how a speaker makes them feel. Aristotle believed the best way to transfer emotion from one person to another is through storytelling. The more personal your content is the more your audience will feel connected to you and your idea.

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Ideas are the currency of the twenty-first century. The ability to persuade, to change hearts and minds, is perhaps the single greatest skill that will give you a competitive edge in the knowledge economy — an age where ideas matter more than ever.

Some economists believe that persuasion is responsible for generating one-quarter or more of America’s total national income. As our economy has evolved from an agrarian to an industrial to a knowledge-based one, successful people in nearly every profession have become those capable of convincing others to take action on their ideas. Think about the role of persuasion in our daily lives:

Entrepreneurs persuade investors to back their startups.

Job candidates persuade recruiters to hire them.

Politicians persuade people to vote for them.

Leaders persuade employees to take specific plans of action.

CEOs persuade analysts to write favorable reports about their companies.

Salespeople persuade customers to choose their product over a competitor’s offering.

In short, persuasion is no longer a “soft skill”— it is a fundamental skill that can help you attract investors, sell products, build brands, inspire teams, and trigger movements. Persuasion is so important to billionaire Warren Buffett that the only diploma he proudly displays in his office is a public-speaking certificate from a Dale Carnegie course. He once told business students that improving their communication skills would boost their professional value by 50% — instantly.

Words and ideas created the modern world, and words and ideas have the potential to make you a star in your field, as long as you can persuade someone else to act on them. Following the tactics of one ancient Greek philosopher can help.

More than 2,000 years ago Aristotle outlined a formula on how to master the art of persuasion in his work Rhetoric. Many great communicators have used it throughout the ages to deliver some of the most influential speeches, presentations, and share their ideas with the world.

To become a master of persuasion yourself and successfully sell your own ideas, try using these five rhetorical devices that Aristotle identified in your next speech or presentation:

1) Ethos or “Character”

To me, ethos represents the part of a speech or presentation when your audience gains some insight into your credibility. Aristotle believed that if a speaker’s actions didn’t back their words, they would lose credibility, and ultimately, weaken their argument.

For example, in a now famous TED Talk on reforming the criminal justice system, Human Rights Attorney Bryan Stevenson begins, “I spend most of my time in jails, in prisons, on death row. I spend most of my time in very low-income communities in the projects and places where there’s a great deal of hopelessness.” You’ll notice that Stevenson does not list his degrees, accomplishments, and awards like he might on a résumé. Instead, he establishes his character for those in the audience who don’t know him. By doing so, he is building a sense of trust between himself and his listeners.

As humans, we are hardwired to search for reasons to trust another person, and we do so quickly. After all, our ancestors had an instant to determine whether a stranger was friend or foe. A simple reminder that you are committed to the welfare of others will build your credibility before you lay out your argument.

2) Logos or “Reason”

Once ethos is established, it’s time to make a logical appeal to reason. Why should your audience care about your idea? If it will save your audience money, for example, they’ll want to know how much it will save them and how the savings will be accomplished. The same reasoning applies to making money. How will your idea help your listeners earn a profit? What steps do they have to take next? These are all logical appeals that will help you gain support. Use data, evidence, and facts to form a rational argument.

3) Pathos or “Emotion”

According to Aristotle, persuasion cannot occur in the absence of emotion. People are moved to action by how a speaker makes them feel. Aristotle believed the best way to transfer emotion from one person to another is through the rhetorical device of storytelling. More than 2,000 years later, neuroscientists have found his thesis accurate. Studies have found that narratives trigger a rush of neurochemicals in the brain, notably oxytocin, the “moral molecule” that connects people on a deeper, emotional level.

In my analysis of 500 of the most popular TED Talks of all time, I found that stories made up 65% of the average speaker’s talk, wheres 25% went to logos, and 10% went to ethos. In other words, the winning formula for a popular TED talk is to wrap the big idea in a story.

What kind of story? TED curator, Chris Anderson, explains, “The stories that can generate the best connection are stories about you personally or about people close to you. Tales of failure, awkwardness, misfortune, danger or disaster, told authentically, hastens deep engagement.” The most personal content is the most relatable.

4) Metaphor

Aristotle believed that metaphor gives language its verbal beauty. “To be a master of metaphor is the greatest thing by far,” he wrote. When you use a metaphor or analogy to compare a new idea to something that is familiar to your audience, it clarifies your idea by turning the abstract into something concrete.

Let’s return to the example of Warren Buffett, one of the savviest practitioners of persuasion. Buffett rarely gives an interview without using metaphor to make his point. When you hear investors say they look for companies surrounded by a moat, for example, it’s a reference to a popular metaphor he established. Buffett has said repeatedly that he looks for companies that are “economic castles” surrounded by moats that make it hard for competitors to enter the industry.

More recently, Buffett gave a speech at the 2017 Berkshire Hathaway annual shareholders meeting, stating that the growth in healthcare spending is the “tapeworm” of the American economy. Through this visceral metaphor, Warren accurately described a serious problem eating away at the foundation of our economic system. Buffett didn’t have to explain what happens when the tapeworm grows bigger. Newspapers and blogs covering the event used “tapeworm” in their headlines.

Those who master the metaphor have the ability to turn words into images that help others gain a clearer understanding of their ideas — but more importantly, remember and share them. It is a powerful tool to have.

5) Brevity

Here again, Aristotle was ahead of his time. “Aristotle had discovered that there are fairly universal limits to the amount of information which any human can absorb and retain,” writes Kings College professor Edith Hall in Aristotle’s Way. “When it comes to persuasion, less is always more.”

Brevity is a crucial element in making a persuasive speech. An argument, Aristotle said, should be expressed “as compactly and in as few words as possible.” He also observed that the opening of a person’s speech is the most important since “attention slackens everywhere else rather than at the beginning.” The lesson here is: start with your strongest point.

The good news for communicators is that Aristotle believed that persuasion can be learned. In fact, according to Hall, he was viewed as “quite threatening” to the political class in ancient Greece when he made the tools of rhetoric available to the masses. They wanted to keep the formula a closely held secret. But Aristotle wanted everyone to have access to it. He championed the idea that a person’s ability to speak and write well, and to use rhetorical devices to change another’s perspective, could unleash human potential and maximize happiness. While the tools we use to communicate ideas have changed in the past two thousand years, the human brain has not. The same formula that worked then will work now.