He will often have to scratch his head, and bite his nails to the quick. [To succeed he will have to puzzle his brains and work hard.]
HoraceNot even for an hour can you bear to be alone, nor can you advantageously apply your leisure time, but you endeavor, a fugitive and wanderer, to escape from yourself, now vainly seeking to banish remorse by wine, and now by sleep; but the gloomy companion presses on you, and pursues you as you fly.
Horace