“When a man does not know what harbour he is making for, no wind is the right wind.”
errant consilia nostra, quia non habent quo derigantur; ignoranti quem portum petat nullus suus ventus est.
Letter LXXI: On the supreme good, line 3
Alternate translation: If one does not know to which port one is sailing, no wind is favorable. (translator unknown).
Epistulae Morales ad Lucilium (Moral Letters to Lucilius)
Context: Our plans miscarry because they have no aim. When a man does not know what harbour he is making for, no wind is the right wind.