When a person is sick, there is always something to be done for him, and done at once. If it is only to open or shut a window, if it is only to tell him to keep on doing just what he is doing already, it wants a man to bring his mind right down to the fact of the present case and its immediate needs.
 Oliver Wendell Holmes Sr., The Poet at the Breakfast-Table (1872). copy citation

Context

“But if a man has n't got plenty of good common sense, the more science he has the worse for his patient. —I don't know that I see exactly how it is worse for the patient,—I said. —Well, I'll tell you, and you'll find it's a mighty simple matter. When a person is sick, there is always something to be done for him, and done at once. If it is only to open or shut a window, if it is only to tell him to keep on doing just what he is doing already, it wants a man to bring his mind right down to the fact of the present case and its immediate needs. Now the present case, as the doctor sees it, is just exactly such a collection of paltry individual facts as never was before,—a snarl and tangle of special conditions which it is his business to wind as much thread out of as he can.” source