Playing with the time, that is : Playing the way they did in those days, but it also can mean the use of rubato... the way they did... (from robare = to steal... [a robber]) : stealing time with one hand, and giving it back with the other... That was usual since the seventeenth century (all the barocks), trough the eighteenth (including Mozart who said that "the left hand is the master, but the right hand does what it pleases it"), and till Chopin, after whom it sort of perverted itself till it became what it is today, except for the violinist Ysaÿe, and after him Rachmaninov who both where still using it... A collection of pieces using that particular type of rubato (Chopin: Nocturnes, studies, Berceuse... Albeniz: Evocaçion, El Puerto)