I cannot afford to throw any extra strain upon it." He smiled at my vehemence.

"Perhaps you are right, Watson," he said.
"I suppose that its influence is physically a bad one.

I find it, however, so transcendently stimulating and clarifying to the mind that its secondary action is a matter of small moment." "But consider!" I said, earnestly.

"Count the cost! Your brain may, as you say, be roused and excited, but it is a pathological and morbid process, which involves increased tissue-change and may at last leave a permanent weakness.

You know, too, what a black reaction comes upon you.