There is not a more difficult feat known than to cut through a cushion with a sword

Richard Whately.

Weak arguments are often thrust before my path; but although they are most unsubstantial, it is not easy to destroy them. There is not a more difficult feat known than to cut through a cushion with a sword.

As quoted in Anecdote Lives of the Later Wits and Humourists (1874) by John Timbs, Vol. 2, p. 44