UNDERSCORE • DICCIONARIO INGLES.COM • Definition of Underscore

... commonplace is genuine commonplace, quite distinct from the tense and pregnant condensation of a lifetime of impassioned experience in Dante or Shakespeare; things that would occur to a bookish country gentleman in after-dinner conversation, the sentiments that such a rare and amiable person would underscore in his Horace. (From a not unimportant angle Ronsard is a minor Horace.) These things are the warp of his poetry; they range from the familiar 'Le temps s'en va' to ...

— Aspects of Literature • J. Middleton Murry