If you watched, listened, or read the transcript to Pope Francis’ speech to Congress on Thursday, you might have noticed a trend: Pope Francis groups ideas into thirds. It’s not a random habit. He does it on purpose.

In a response to a question Pope Francis once said, “I will talk about three things: one, two, three, like the old-time Jesuits used to do, okay? One, two three.” As a Jesuit-trained communicator Francis understands and obeys certain rules of writing and persuasion. The rule of three is one very powerful and effective guideline. It simply states that, in short term memory, we can recall words, themes, or ideas when they are grouped in threes. The greatest works of literature are grouped in three, as are famous quotes, and famous speeches. Here are several examples of the rule of three in Pope Francis’ historic speech [groups of three are in bold].

-Elected members of congress have been “invited, called and convened by those who elected you.”

-”I would like to take this opportunity to dialogue with the many thousands of men and women who strive each day to do an honest day’s work, to bring home their daily bread, to save money and –one step at a time – to build a better life for their families.”

– “A people with this [American] spirit can live through many crises, tensions and conflicts.”

– “A delicate balance is required to combat violence perpetrated in the name of a religion, an ideology or an economic system, while also safeguarding religious freedom, intellectual freedom and individual freedoms.”

– “Our efforts must aim at restoring hope, righting wrongs, maintaining commitments.”

-“The complexity, the gravity and the urgency of these challenges demand that we pool our resources and talents.”

– “I am happy that America continues to be, for many, a land of dreams. Dreams which lead to action, to participation, to commitment. ”

– “We must not be taken aback by their [immigrant] numbers, but rather view them as persons, seeing their faces and listening to their stories, trying to respond as best we can to their situation.”

– “In a word, if we want security, let us give security; if we want life, let us give life; if we want opportunities, let us provide opportunities.”

– “So many others [youth] seem disoriented and aimless, trapped in a hopeless maze of violence, abuse and despair.

The rule of three is a fundamental building block of persuasion. Pope Francis, who writes many of his speeches himself, is a masterful writer and understands that words and language can move people to action.