Why is a raven like a writing desk?

For instance, suppose it were nine o’clock in the morning, just time to begin lessons: you’d only have to whisper a hint to Time, and round goes the clock in a twinkling! Half-past one, time for dinner!

*trembling* I’m a poor man, your Majesty, —and I hadn’t begun my tea—not above a week or so—and what with the bread-and-butter getting so thin—and the twinkling of the tea—