Caesura Literary Term is a grammatical pause or break in a line of poetry (like a question mark), usually near the middle of the line.

rhythm A caesura is usually dictated by sense or natural speech rhythm rather than by metrics. In poetry scansion, a caesura is usually indicated by the symbol //. The caesura can also be used for rhetorical effect, as in "To err is human; || to forgive, divine." by Alexander Pope

Here are the same lines in modern English from Burton Raffel’s translation: Out from the marsh, from the foot of misty Hills and bogs, bearing God’s hatred, Grendel came, hoping to kill Anyone he could trap on this trip to high Herot.  Punctuation reproduces pause effect of the caesura.

Latin Cynthia prima fuit; || Cynthia finis erit. ("Cynthia was the first; Cynthia will be the last" — Propertius)Propertius Bible (for all the gods of the Pagans are nothing, but the Lord made heaven)Lord Old English Hwæt! we Gar-Dena || on geardagum ("Lo! we Spear- Danes, in days of yore...")

So, if we were to lineate Sing a Song of Six-Pence as Beowulf’s author might have, it might look like this (caesuras marked): Sing a song of sixpence, || a pocket full of rye. Four and twenty blackbirds, || baked in a pie. When the pie was opened, || the birds began to sing; Wasn’t that a dainty dish, || to set before the king? The king was in his counting house, || counting out his money; The queen was in the parlour, || eating bread and honey. The maid was in the garden, || hanging out the clothes; When down came a blackbird || and pecked off her nose.

Once upon a midnight dreary, || while I pondered weak and weary, Over many a quaint and curious || volume of forgotten lore, While I nodded, nearly napping, || suddenly there came a tapping, As of someone gently rapping, || rapping at my chamber door. `’Tis some visitor,’ || I muttered, || `tapping at my chamber door - Only this, and nothing more.’ Ah, distinctly I remember || it was in the bleak December, And each separate dying ember|| wrought its ghost upon the floor. Eagerly I wished the morrow; – || vainly I had sought to borrow From my books surcease of sorrow – || sorrow for the lost Lenore - For the rare and radiant maiden || whom the angels named Lenore - Nameless here for evermore.