I who am mercurial in temperament, for example, can take any amount of Indian hemp without being made ill by it; while ten drops will send some slow and torpid rustics mad drunk with excitement--drive them into homicidal mania." Sebastian nodded his head.

He needed no more explanation.

"You have hit it," he said.

"I see it at a glance.

The old antithesis! All men and all animals fall, roughly speaking, into two great divisions of type: the impassioned and the unimpassioned; the vivid and the phlegmatic.