In Beowulf, the theme of impermanence is prominent throughout the story. A man's fortune can take a grim turn at any moment, so the celebration of a joyful time is usually short-lived. The experience of being a human often means that fate can change at any time, and sometimes not in the direction that one might wish. Beowulf is directly affected by this transience throughout the poem, which is full of examples supporting the idea that fortune is a temporary thing.
A major theme in Beowulf is that joy and glory can never survive forever. After Beowulf's victory over Grendel, Hrothgar (the king of the Danes) gives a lengthy speech about the likelihood of imminent failure in all situations of happiness and well-being. Even Hrothgar, who has enjoyed so much success due to his generosity and goodness, experiences the dangers of temporarily assuming that such joy can last. He brings prosperity to the Danes over his fifty years of successful ruling; his achievements are best noticed in his construction of the mead hall Heorot, which represents the protection Hrothgar offers his people. (Indeed, Grendel's vicious attacks upon Heorot--a clear symbol of the successes of the Danes-serve as reminders of the instability of fortune and how easily things can make a turn for the worse.) Yet, there is a terrible impermanence with age, and the elderly king feels this fact personally. As a result, he tries to impart this knowledge (and some eloquent advice) to Beowulf. In his speech honoring the brave hero, Hrothgar warns that there is an "ugliness of age" and that a man's "eyes' brightness lessens and grows dim." All good rulers grow old, and are thus unable to defend their kingdoms without additional help, which in this case comes in the form of Beowulf. Still, even Beowulf cannot escape the ultimate inevitability that "the frail house of flesh must crumble and fall at its hour." Hrothgar uses his own life as example to his argument: "I swayed the Ring-Danes for fifty years here, defending them in war . . . But what change of fortune befell me at my hearth with the coming of Grendel." The king is victorious for so long that Grendel's attacks make Hrothgar's downfall seem deeply tragic. One cannot maintain victory for all time, and in Hrothgar's experience, "grief sprang from joy when the old enemy entered our hall." Hrothgar realizes that the gifts of happiness and triumph can also ultimately lead to a man's downfall. Such luck can only ever result in vanity and the eventual fall of a once powerful person, according to Hrothgar. He warns Beowulf to "resist this deadly taint . . . put away arrogance . . . the noon of your strength shall last for a while now, but in a little time sickness or a sword will strip it from you." As Hrothgar believes, nothing positive will last, and no one is immune from the uncertainty of fortune and time.
This notion that glory can, and will, disappear is also evident in Beowulf's rise to the throne and in his long reign as the king of the Geats. Two kings (that are mentioned in the story) are killed in battle before Beowulf can even ascend to real power. It seems that all kings, whether good or bad, risk a change in the fortune and circumstances of their ruling. Regardless of Hygelac's reputation as a "kindly lord of the peoples, the king of the Geats," he still is killed "among the hurl of battle slaked the sword's thirst on the soil of Friesland and the blows beat down on him!" Hygelac's son, Heardred, quickly meets death as well after taking command, when he is slain by Onela, king of the Scylfings. Heardred's "hospitality cost him a weapon-thrust and a wound to the life." This proves that when a man believes that he is doing well in the world it is often the time when his fortune will change adversely. With Heardred's death, Beowulf becomes king, ruling successfully for many years, having "survived unscathed each of these combats, calamitous onslaughts, works of prowess: until this one day when he must wage war on the serpent." Thus, his ability to stay powerful is no match for the impermanence of glory and triumph; a king's supremacy can only last so long. In this instance, the dragon puts an abrupt stop to Beowulf's prosperity, and there is probably nothing Beowulf could have done to prevent this change. In keeping with the theme, it is clear that man cannot shield himself from the likelihood of an outside force (or, more generally, fate) in determining how one's fortune will develop.
In the final battle against the dragon, the gold that Beowulf fights to preserve for his people ultimately is worthless to anyone, lending another example to the idea that time and glory are mutable entities. When the wealth is buried with Beowulf, it is lost forever and no one will ever really value what Beowulf fought to bring to the Geats. Indeed, the dragon is guarding a fantastic hoard of treasure that is in itself useless. The magnificence that sits under the dragon's watchful eye can never be appreciated as it is, so the triumph and success of the men who had first stockpiled all of the riches eventually slips away with time. Nothing is ever permanent in life, particularly in the case of material objects that one might consider to be timeless and valuable.
Rather than focusing solely on the impermanence of physical things, the poem touches on the uncertainty of loyalty in men as well. When Beowulf is battling the dragon, he needs the assistance of his warriors more than ever. He has supported these men by providing shelter and lavish feasts, among other things. In return, one would expect the knights to protect their king when the time came. Time proves, though, that the loyalty of the men is not strong enough to keep Beowulf safe. Interestingly, before they set out for the fight, Beowulf addresses his men with a rousing speech, assuring them that "this affair is not for you, nor is it measured to any man but myself alone." The men take him too much at his word, because the dragon attacks and seems to be a formidable opponent to Beowulf by himself, powerful enough to severely wound the brave king ("the band of picked companions did not come to stand about him, as battle-usage asks . . . they escaped to the wood, saved their lives"). Only the young warrior Wiglaf is willing to valiantly defend the life of his leader. Wiglaf pleads with the other men (who have cowardly fled to hiding): "Let us go to him, help our leader for as long as it requires . . . I had far rather that the flame should enfold my flesh-frame there alongside the gold-giver." He bravely states that it "would seem unfitting to me, unless first we have been able to kill the foe and defend the life of the prince of the Weather-Geats." Clearly, the devotion of Beowulf's warriors was only temporary, even when Wiglaf reminds them about "taking mead in the banqueting hall, when we bound ourselves to the gracious lord who granted us arms, that we would make return for these trappings of war, these helms and hard swords, if an hour such as this should ever chance for him." The steadfastness of the knights is completely gone at the first sign of real danger, no matter how angry Wiglaf's reproach is. As the theme suggests (yet again), the world is full of impermanence, of things that do not survive forever.
As Beowulf 's theme points out, all good things are likely to be mere moments in time that can be altered at any minute. Celebrating victories may be enjoyable for a while, but triumph can lead to vanity, downfall, or a general turn to bad luck. Beowulf himself experiences this lack of perpetual stability when he is killed after becoming a king. His good fortune survives only until the instant when the inevitable dread appears. It seems that the poem is making a suggestion that people only move forward on a path of happiness and joy until they hit a wall, an unavoidable barrier that will plague every living thing. This impermanence is the only certainty anyone can have, particularly in Beowulf's world, where glory, loyalty, and greatness all are fleeting.