Story highlights Michael D'Antonio is the author of "The Truth About Trump"

He said he liked Turmp "when he's quieter like that."

(CNN) — Over the course of several hours worth of personal and candid conversations with Donald Trump, author Michael D'Antonio said Wednesday that he saw a very a different person than the one who galvanized supporters and stoked controversy throughout the presidential campaign.

"In public, he only has one speed," D'Antonio said Wednesday on CNN's "New Day." "And it's at bombast and aggression."

D'Antonio, a Pulitzer Prize-winning journalist, spent considerable time interviewing the Republican presidential nominee in 2014, material he later used in a biography titled, "The Truth About Trump," which he also discussed with CNN over the summer.

Those interviews, D'Antonio said Wednesday, reveal "a calmer, more sincere, reflective person."

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