Dr. Stitchem was trying very hard to convince Percy that he should give up drinking.

"Ever notice a cactus plant?" he asked Percy. "If you pour water around its roots it thrives, turns greener, and grows bigger. Take the same cactus plant. Pour vile liquor on it and what happens? It shrivels, it shrinks, it dies. Doesn't this teach you anything?"

"Yes," said Percy. "If you want a cactus growing in your stomach drink water."