King Arthur's adamantine shield of faith

But all that was not such, as seemd in sight,

Before that shield did fade, and suddeine fall:

And when him list the raskall routes appall,

Men into stones therewith he could transmew,

And stones to dust, and dust to nought at all;

     Edmund Spenser, The faerie queene I.vi.35, ll. 3-7.