It is said that Abraham Lincoln had a high-pitched voice with a shrill quality to it. When he began his speeches, the audience at first wondered if this tall man was indeed the great orator of whom they had heard.

But as Lincoln’s words washed over them and Lincoln fell into a rhythm, the audience was soon mesmerized—both by the words they heard and how they were delivered.

When Harvard Business School Professor Clayton Christensen began a speech, it was similar. Instead of thunder and lightning, his speech was slow and methodical, soft and unassuming. Even before his ailments had struck at his ability to speak, the audience often wondered at the beginning of a talk whether this tall man—he was 6’8”—was the great mind they had come to hear.

But as Christensen dove into his stories and began teaching how the world worked—not how we wished it would work, but how it actually worked—he gained steam and cast a spell over the audience that became mesmerized—both by the points he made and how they were said.