Inexplainable

The rider himself after a time becomes infected with this inexplainable desperation of terror, and I suppose I must have done so; but for a time I kept the upper hand.

[…]kneeling down before my dead betrothed, I kissed her cold white hand with sincere compunction, before attempting the garbled and probably totally incoherent story with which I endeavoured to explain the inexplainable situation.