"It usually takes more than three weeks to prepare a good impromptu speech.”    —Mark Twain

Quotations are a favorite device of public speakers. Often used as attention grabbers, quotations can support or illustrate a speaker’s ideas. Effective introductory quotations set the tone and framework for the speech. Some quotations are used because they lend authority to the speaker or because they sound artful—a quote from a famous writer like Henry David Thoreau is convincing both because Thoreau said it and because of the eloquence of his words. However, quotations should not replace your own words or overshadow your message.

Incorporating Quotations

Besides using quotations as a powerful way to begin or end a speech, you can use them to illustrate or highlight a main point or as transitions to separate the major parts of a speech. An effective technique is to present transitional quotes on a slide with a relevant visual such as a photograph.
Always acknowledge your sources in a speech, including quotations. Cite every source clearly (1) while speaking, (2) on a handout, or (3) on a slide. For example, while speaking, you might tag the quotation so the audience knows when the quote begins and ends. In the example that follows, the tag—the part explaining the quote’s source—is bolded.
Ex. According to authors Strunk and White, “The habitual use of the active voice . . .  makes for forcible writing.” [Voice change or pause indicates the end of the quotation.] They advise writers to check sentences for passive voice and consider revising them to use active voice.
 
Note that the ellipsis (the three dots) indicates the word “however” was deleted from its place in the original text (shown below). In order to make a quotation fit smoothly into your speech, you can delete a word or phrase from it or make small adjustments in the wording, as long as the original meaning is preserved.
Alternatively, you might write out a quotation on a handout or slide and give the complete source information (the author, title, place and date of publication, and so on).
Ex. “The habitual use of the active voice, however, makes for forcible writing. This is true not only in narrative principally concerned with action, but in writing of any kind. Many a tame sentence of description or exposition can be made lively and emphatic by substituting a transitive in the active voice for some such perfunctory expression as there is, or could be heard.”

-- William Strunk and E. B. White.The Elements of Style. 4th ed. NY: Longman, 1999.
No matter which method you select —speech, handout, or slide—you should always let your audience know when you are citing a source directly (using the exact words of the author) or paraphrasing your source (putting someone else’s ideas into your own words). The following is an example of the same passage from Strunk and White but paraphrased rather than quoted directly. Notice that the speaker still acknowledges the source.
Ex. As Strunk and White see it, writers should always check sentences for passive voice and consider revising them to use active voice. The active voice, in their opinion, is preferable because of its strength and clarity.

Direct Quoting versus Paraphrasing

Direct quotations are most effective when they are brief, when they convey your message more clearly than you would, and when they are particularly witty, compelling, or articulate.
Paraphrasing is better than using direct quotations when a quote’s wording is too difficult for listeners to understand quickly or uses technical language or jargon.  It’s also better to paraphrase if a quote is longer than two or three sentences.

Pitfalls and Perils

It’s a good idea to keep quotations short because you want to focus on your ideas and not bore the audience by reading long passages aloud. Likewise, be wary of overusing quotations; the audience is there to hear what you have to say.
Avoid quotations that have no relevance to your speech; carefully consider a quotation’s purpose and its benefits to your presentation.
Consider your audience. If you are speaking to people who may not know who Plato is, there is no point in using his name. Instead, refer to him as “an ancient Greek philosopher.” In the example above, a group of English teachers would recognize Strunk and White as the authors of the famous writing manual, The Elements of Style. Their names won’t be significant, though, for audiences who haven’t read much about writing. For these audiences, you would probably want to provide a clue to their identity, like “Strunk and White, who wrote a much-loved writing manual called The Elements of Style . . .”
If you use a maxim or proverb, you don’t need to cite. Although you don’t want to fill your speeches with clichés, a well-placed proverb or maxim can help your audience understand or relate to your point.
Many websites and reference books suggest familiar quotes for speeches, such as this handout’s opening line from Mark Twain. In general, if the quote is simply for interest or to add style to your speech, it is sufficient to acknowledge the original author. If, however, you are using the quote as evidence to support a point or lend authority to your argument, cite the full source.