I found this looking online for secondary sources:
" 'Pure' evil requires exclusion. It is evil undiluted, two hundred proof, served in an old fashioned shot glass and taken neat, without a chaser. It is all evil and nothing but evil, and its impact is unweakened as it ages."
I thought that was pretty clever and true. It goes back to what Coach Crook said about the essence of evil being too potent for us to handle.