Parece ser uma citação real de "O Manual do Imperador: Uma Nova Tradução das Meditações" por C. Scot - e David V. Hicks como você pode ver em Google Livros .
A passagem é encontrada no Livro Quatro "verso" 49.
49 > Be like a rocky promontory against which the restless surf continuously pounds; it stands fast while the churning sea is lulled to sleep at its feet. I hear you say, "How unlucky that this should happen to me!" Not at all! Say instead, "How lucky I am that I am not broken by what has happened and am not afraid of what is about to happen. The same blow might have struck any one, but not many would have absorbed it without capitulation and complaint."