Disappointed when I went somewhere and there wasn't any tea,
Enthralled by a story about someone guarding a mystical treasure alone in a remote museum on a dark and stormy night,
Sympathetic toward a hardworking guy nobody likes, but also aggravated by his bossiness to the point of swearing at him,
Confused due to waking up at 7 pm and not being sure how it happened.
You probably don't entirely understand any of those. What is it to entirely understand something? But you probably get the idea in each case.
Disappointed when I went somewhere and there wasn't any tea,
Enthralled by a story about someone guarding a mystical treasure alone in a remote museum on a dark and stormy night,
Sympathetic toward a hardworking guy nobody likes, but also aggravated by his bossiness to the point of swearing at him,
Confused due to waking up at 7 pm and not being sure how it happened.
You probably don't entirely understand any of those. What is it to entirely understand something? But you probably get the idea in each case.