In cases in which it's appropriate.
Given the question, were you expecting somebody to answer with a zen koan? Yunyan asked Daowu, “How does the Bodhisattva of Great Compassion [Kannon] use so many hands and eyes?” Daowu answered, “It’s just like a person in the middle of the night reaching back in search of a pillow.”
Yunyan said, “I understand.” Daowu asked, “How do you understand it?” Yunyan answered, “All over the body are hands and eyes.”
Daowu said, “What you said is all right, but it’s only eighty percent of it.” Yunyan responded, “I’m like this, senior brother. How do you understand it?” Daowu explained, “Throughout the body are hands and eyes.”