Shield was still thriving when his time came and he crossed over into the Lord's keeping. His warrior band did what he bade them when he laid down the law among the Danes: they shouldered him out to the sea's flood, the chief they revered who had long ruled them. A ring-whorled prow rode in the harbour, ice-clad, outbound, a craft for a prince. They stretched their beloved lord in his boat, laid out by the mast, amidships, the great ring-giver. Far-fetched treasures were piled upon him, and precious gear. (26-37)
Beowulf begins with death – with the description of the lavish burial-at-sea of the Danish king, Shield Sheafson. This is the first funeral scene in the epic, but it certainly won't be the last. It lets us know right away that how a man dies (preferably when he is "still thriving") and how he is buried (preferably with a huge load of "precious gear") reflects on who he was when he was alive.
None of them expected he would ever see his homeland again or get back to his native place and the people who reared him. They knew too well the way it was before, how often the Danes had fallen prey to death in the mead-hall. (691-696)
Beowulf doesn't enter into his battle with Grendel expecting to triumph over the demon. Instead, he is able to fight Grendel with courage because he's already accepted that he will probably die in the attempt. This morbid outlook frees him from fear. After all, if you accept the worst possible outcome, there's nothing left to make you afraid.
But death is not easily escaped from by anyone: all of us with souls, earth-dwellers and children of men, must make our way to a destination already ordained where the body, after the banqueting, sleeps on its deathbed. (1001-1007)
Not only does this passage emphasize that death is inevitable; it also compares life and death to the "banqueting" and battle that medieval warriors experience on a daily basis.
"[…] she has taken up the feud because of last night, when you killed Grendel, wrestled and racked him in ruinous combat since for too long he had terrorized us with his depredations He died in battle, paid with his life; and now this powerful other one arrives, this force for evil driven to avenge her kinsman's death. Or so it seems to thanes in their grief, in the anguish every thane endures at the loss of a ring-giver, now that the hand that bestowed so richly has been stilled in death." (1333-1344)
Grendel's mother sets out to avenge her son's death by killing someone from the tribe that killed him. This type of revenge killing was common in medieval European warrior culture, suggesting that Grendel and his mother are more human than you might have thought.
"Wise sir, do not grieve. It is always better to avenge dear ones than to indulge in mourning. For every one of us, living in this world means waiting for our end. Let whoever can win glory before death. When a warrior is gone, that will be his best and only bulwark." (1384-1389)
Although the narrator of Beowulf has a Christian, Anglo-Saxon perspective, the characters in the poem believe that the only protection warriors have in the afterlife is the force of their reputation. In other words, Geat and Dane warriors aren't trying to get into Heaven – they're trying to leave tales of their great deeds behind them.
Beowulf got ready, donned his war-gear, indifferent to death (1441-1442)
In a few words, the narrator sums up Beowulf's attitude toward mortality: he is "indifferent to death," realizing that it will eventually come to him, and not caring at all. While he lives, he will do great deeds. Eventually, he has accepted that he will die. That's all there is to it.
"Choose, dear Beowulf, the better part, eternal rewards. Do not give way to pride. For a brief while your strength is in bloom but it fades quickly; and soon there will follow illness or the sword to lay you low, or a sudden fire or surge of water or jabbing blade or javelin from the air or repellent age. Your piercing eye will dim and darken; and death will arrive, dear warrior, to sweep you away." (1759-1768)
Hrothgar reminds Beowulf that he shouldn't get too cocky; after all, no matter how many great deeds he performs, there will eventually be some kind of catastrophe that kills him. He may have nearly superhuman strength, but something will be his downfall anyway. Death comes to us all in the end.
"You are the last of us, the only one left of the Waegmundings. Fate swept us away, sent my whole brave high-born clan to their final doom. Now I must follow them." That was the warrior's last word. He had no more to confide. The furious heat of the pyre would assail him. His soul fled from his breast to its destined place among the steadfast ones. (2813-2820)
With his last words, Beowulf recalls the now-deceased members of his clan, passing on their history and fame to Wiglaf. Death is not always just the loss of a single life; eventually whole clans, whole tribes, and whole nations are lost.
The Geat people built a pyre for Beowulf, stacked and decked it until it stood four-square, hung with helmets, heavy war-shields and shining armour, just as he had ordered. Then his warriors laid him in the middle of it, mourning a lord far-famed and beloved. On a height they kindled the hugest of all funeral fires; fumes of woodsmoke billowed darkly up, the blaze roared and drowned out their weeping, wind died down and flames wrought havoc in the hot bone-house, burning it to the core. (3137-3148)
Beowulf's funeral pyre is the final image of the epic, creating an interesting parallel to the opening scene, Shield Sheafson's burial at sea.