Once speakers identify the specific purpose, they must next figure out the central idea. The central idea gets expressed as a single sentence that articulates the one thought the presenter wants the audience to remember at the end of the speech. This might sound an awful lot like a specific purpose, and many novice speakers confuse the two concepts and use their specific purpose as their central idea. However, they are not the same, and to clarify the difference, try thinking of the central idea in a more familiar term, one which most people have likely heard before in a writing class: a thesis statement. A thesis statement concisely presents an assertion or proposition that the speaker must then support with evidence.

One method to help determining a central idea is to answer the specific purpose as though it leaves a question unanswered, such as why or what. If the specific purpose is “To inform the audience about the effects of mindfulness on health,” then the question unanswered by this statement is, what? What does the speaker want the audience to know about the effects of mindfulness on health in a single sentence? In other words, what is the central idea behind this purpose that will ultimately lead to achieving that goal?

Keep the central idea simple, yet focused. If preparing a 6- to 8-minute speech informing an audience of the causes for the Industrial Revolution, the central idea “The history of Western civilization is complex” would not work well. Such a central idea is too broad and vague, opening up the possibility to present a speech with far too much information for the speaker to cover in that short time period. Instead, the speaker should want a more specific central idea that more specifically summarizes the content of the speech, as the following example demonstrates:

“Beginning with Gutenberg’s printing press, the explosion of information-sharing in Western civilization led to rapid technological development.”

Think of the speech as a delicate and exquisite sauce that a master chef needs to make. In making a sauce, the cook gathers together all of the ingredients (information from various sources); mixes it together in an orderly, careful, and measured fashion (the process of composition); and then applies heat and simmers it, thereby reducing the liquid to a rich, powerfully flavored sauce that ignites the taste buds. The central idea remains when the entire speech gets boiled down into just one carefully worded, yet rich, sentence, encompassing the whole message.

Referencing the specific purpose regarding the effects of mindfulness on health, an ideal central idea could look something like this: Developing mindfulness through regular practice produces benefits in all aspects of life, from mental health to physical well-being. Note that the sentence is complete, grammatically correct, asserts a perspective, and includes just enough information from which to derive the main points. From this single sentence, speakers can write a speech about mindfulness, the practices that nurture it, and the physical and mental benefits individuals might expect from doing so. This central idea, once written, supports the specific purpose and becomes the hinge around which everything else in the speech will revolve.

Keep in mind that the central idea may need to remain flexible during the research phase of preparing the speech in order to tailor the information specifically to the audience. The specific purpose, regardless, remains the same. Different audiences may require different methods to relay the same message, so keep the central idea fluid until more information is known about their preferences.