text: Men think that we are in retirement, and yet we are not. For if we have sincerely retired, and have sounded the signal for retreat, and have scorned outward attractions, then, as I remarked above, no outward thing will distract us; no music of men or of birds can interrupt good thoughts, when they have once become steadfast and sure. The mind which starts at words or at chance sounds is unstable and has not yet withdrawn into itself; it contains within itself an element of anxiety and rooted fear,
  and this makes one a prey to care, as our Vergil says: