"I know that men are won over less by the written than by the spoken word, that every great movement on this earth owes its growth to great orators and not to great writers." —Adolf Hitler writing in "Mein Kampf," 1925

In more than 5,000 persuasive speeches, Nazi leader Adolf Hitler bewitched his audiences in an altered and rehearsed voice.

Hitler's voice was described as overwhelmingly powerful and "spellbinding" by French-American novelist George Steiner in Ron Rosenbaum's book "Explaining Hitler."

"I was born in 1929, so from '33 on my earliest memories are sitting in the kitchen hearing the voice [of Hitler] on the radio," Steiner shared with Rosenbaum.

"It's a hard thing to describe, but the voice itself was mesmeric ... The amazing thing is that the body comes through on the radio. I can't put it any other way. You feel you're following the gestures," Steiner said.

Remarkably, the Nazi leader's normal voice was largely unknown outside of Hitler's terrifying inner circle.

But in 1942, a Finnish sound engineer secretly recorded a conversation between Finland's defense leader, Carl Gustaf Emil Mannerheim, and Hitler.

Before the engineer was caught by the SS, he managed to record 11 minutes of candid audio.

Here's the audio clip:

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And here's the voice Hitler used in his speeches:

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Further, American psychologist Henry Murray describes the Nazi dictator's overall presence as "hypnotic" in "The Personality of Adolf Hitler," a 229-page report that was commissioned in 1943 by the US Office of Strategic Services, a precursor to the CIA.

According to Murray's report, Hitler received frequent compliments on his grayish-blue eyes, even though they were described as "dead, impersonal, and unseeing."

Hitler was slightly below average in height and had a receding hairline, thin lips, and well-shaped hands.

Murray notes that the merciless Nazi leader was known to offer a weak handshake with "moist and clammy" palms, and was awkward at making small talk.

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