Letters 109.15

Moreover, it is in accordance with Nature to show affection for our friends, and to rejoice in their advancement as if it were absolutely our own. For if we have not done this, even virtue, which grows strong only through exercising our perceptions, will not abide with us. Now virtue advises us to arrange the present well, to take thought regarding the future, to deliberate and apply our minds; and one who takes a friend into council with him, can more easily apply his mind and think out his problem.

Therefore he will seek either the perfect wise man or one who has progressed to a point bordering on perfection. The perfect wise man, moreover, will help us if he aids our counsels with ordinary good sense.

Seneca, Letters to Lucilius 109.15, translated by Richard Mott Gummere