"The hallmark of creative people is their mental flexibility... Sometimes they are open and probing, at others they're playful and off-the-wall. At still other times, they're critical and faultfinding. And finally they're doggedly persistent in striving to reach their goals."
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Source : Roger Von Oech (1986). “A Kick in the Seat of the Pants: Using Your Explorer, Artist, Judge, & Warrior to Be More Creative”, Harper Perennial
