✦ Sir Galahad, Tennyson, 1842 ✦
"My good blade carves the casques of men,
my GOOD · BLADE · CARVES the · CASQUES of · MEN
⏑ — ⏑ — ⏑ — ⏑ —iambic tetrameter (4 beats)
casques KASKS — helmets (from French casque). The line means: my sword cleaves the helmets of men.
My tough lance thrusteth sure,
my TOUGH · LANCE · THRUST-eth · SURE
⏑ — ⏑ — ⏑ — ⏑iambic trimeter (3 beats)
thrusteth THRUST-eth — archaic 3rd-person singular ending, like doeth, maketh. The line shortens — three beats, not four — and lands harder for it.
My strength is as the strength of ten,
my STRENGTH · is AS · the STRENGTH · of TEN
⏑ — ⏑ — ⏑ — ⏑ —iambic tetrameter (4 beats)
Because my heart is pure" —
be-CAUSE · my HEART · is PURE
⏑ — ⏑ — ⏑ —iambic trimeter (3 beats)
The promise the whole poem is grieving. Galahad has spent his life inside this line — and has just learned that the strength of ten doesn't fix anything if it serves the husbandry.