'Et quando' inquis 'tibi proderit istud quod in exitu discis, aut in quam rem?' In hanc, ut exeam melior. ... Hoc est huius boni tempus: quisquis senex ad sapientiam pervenit, annis pervenit. Epistulae ad Lucilium Liber VII Ep. LXVIII.xiv.
"'And when, you say, will what you learn on leaving be useful to you, or for what?' In this: that I will leave [a] better [man]. ... That is the time of this good: whoever comes to wisdom in old age, comes to it through years." 68th Letter to Lucilius xiv.
And these years are years of "many experiences" (multis experimentis xiv) in which you "hide yourself in leisure; but also hide this leisure itself" (absconde te in otio; sed et ipsum otium absconde i) and "speak with yourself" (ipse tecum loquaris vi).