Jonathan Stroud said this quote

“ When you go out hunting wicked spirits, it's the simple things that matter most. The silvered point of your rapier flashing in the dark; the iron filings scattered on the floor; the sealed canisters of best Greek Fire, ready as a last resort... But tea bags, brown and fresh and plenty of them, and made (for preference) by Pitkin Brothers of Bond Street, are perhaps the simplest and best of all. OK, they may not save your life like a sword-tip or an iron circle can, and they haven't the protective power of a sudden wall of fire. But they do provide something just as vital. They help keep you sane. ”