...of concentration

Unfortunately for the Republic, it was not a third-rate mediocrity that was sitting at the microscope. No, it was Professor Persikov that sat there! The whole of his life and his thoughts were concentrated in his right eye. For some five minutes, in stony silence, a superior being observed an inferior one, tormenting and straining its eye over the preparation that stood out of focus. All around was silent.

[The Fatal Eggs, Bulgakov, M.]