“Of course, however, the living voice and the intimacy of a common life will help you more than the written word. You must go to the scene of action, first, because men put more faith in their eyes than in their ears, and second, because the way is long if one follows precepts, but short and helpful, if one follows patterns.”
Plus tamen tibi et viva vox et convictus quam oratio proderit; in rem praesentem venias oportet, primum quia homines amplius oculis quam auribus credunt, deinde quia longum iter est per praecepta, breve et efficax per exempla.
Alternate translation: Teaching by precept is a long road, but short and beneficial is the way by example.
Source: Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter VI: On precepts and exemplars, Line 5.