You have been called to hold a high position, but not a safe one; a sublime position, but not a secure one. How terrible, how very terrible is the place you hold!

-St Bernard of Clairvaux
c.1145  Letter to Eugenius III shortly after he had became Pope, on the dangers of the growth of papal power. Collected in B S James (ed and trans)  The Letters of St Bernard of Clairvaux (1953).

It hath been often said, that it is not death, but dying, which is terrible.

-Fielding, Henry
Amelia, bk.3, ch.4.

I have spoken so far only of the blissful visionary experience† But visionary experience is not always blissful. It's sometimes terrible. There is hell as well as heaven.

-Huxley, Aldous Leonard
  Heaven and Hell.

No, I never heard nothing about it, but when they name any disease after two guys, it's got to be terrible!

-Puzo, Mario
On Guillain-Barre¤   syndrome. Quoted in Heller andVogel No Laughing Matter (1986).

Swiftly walk o'er the western wave, Spirit of Night! Out of the misty eastern cave, Where, all the long and lone daylight, Thou wovest dreams of joyand fear, Which make thee terrible and dear, Swift be thy flight!

-Shelley, Percy Bysshe
'To Night' (published1824).