Plutarch Demetrius 52

[1] But Demetrius, who in the beginning bore up under the misfortune that had come upon him, and presently grew accustomed to it and endured his situation with a better grace, at first, in one way or another, exercised his body, resorting to hunting, so far as he could, or riding; then, little by little, he came to have the greatest indifference and aversion to these sports, took eagerly to drinking and dice, and spent most of his time at these.

[2] This was either because he sought escape from the thoughts on his present condition which tormented him when he was sober, and tried to smother his reflections in drunkenness; or because he had convinced himself that this was the real life, which he had long desired and striven to attain, but had foolishly missed it through folly and empty ambition, thereby bringing many troubles upon himself, and many upon others; he had sought in arms and fleets and armies to find the highest good, but now, to his surprise, had discovered it in idleness and leisure and repose.

[3] For what other end than this can worthless kings seek to attain by their wars and perils? Wicked and foolish indeed are they, not only because they seek after luxury and pleasure instead of virtue and honour, but also because they do not even know how to enjoy real pleasure or true luxury.
  So, then, Demetrius, after an imprisonment of three years ¹ in the Syrian Chersonese, through inactivity and surfeit of food and wine, fell sick and died, in the fifty-fifth year of his life.

[4] Seleucus was in ill repute for this, and repented him bitterly for having cherished such suspicions against Demetrius, and for allowing himself to be outdone even by Dromichaetes, a barbarous Thracian, who had given Lysimachus, ² his captive, a treatment so humane and royal.