|Inhabitants||Valar, Maiar, Elves, Men, Dwarves|
|Description||A world once good but corrupted by Morgoth's rebellion|
|Other names||Arda Hastaina|
|Etymology||Q. arda 'realm' + hastaina, 'marred'|
"For even if we under Eru have the power to return to Middle-earth and cast out Morgoth from the Kingdom of Arda, we cannot destroy all the evil that he has sown, nor seek out all his servants—unless we ravaged the whole of the Kingdom and made an end of all life therein; and that we may not do." —Mandos, from The Peoples of Middle-earth
 History of Arda's Marring
Though all of Eä was tainted from its beginning by Melkor's rebellion against Eru during the Music of the Ainur, Arda sustained far worse wounds than the rest of creation due to the direct meddling of Melkor-Morgoth. In fact, the phrase "Arda Marred" is typically used specifically with this extra damage in mind, but unjust misfortune could occur even in areas where Melkor's stain was negligible, such as Aman.
Melkor followed the Valar to Arda in the beginning of its history, and endeavored to undo all of their labors in building the Earth for the Children of Ilúvatar. According to The Silmarillion, Melkor tried to fill in all the valleys made by the Valar, and level their mountains. Even so, Arda's form became more stable over time—but never in quite the fashion that the Valar had intended.
 Corruption of the Spring of Arda
Yet more insidious and damaging to Arda was Melkor's corruption of its first Spring. He entered the north of Middle-earth and there began building his first fortress, Utumno. From it, a vast evil influence spread, sickening and killing many plants and animals. This poisonous effect of Melkor's hatred also brought about the existence of choking weeds, fens that provided a breeding ground for flies, and animals preyed cruelly upon each other. Thus, the beautiful Spring of Arda came to an abrupt end.
When the Valar realized what had happened, Melkor made war against them and destroyed the two lamps they had built to light Arda. In the chaos of the war and the lamps' fall, the lands of Middle-earth were broken, the seas "arose in tumult", and fire consumed many of the things the Valar had made. The original symmetry of Arda's lands was permanently lost. Thus did Arda's very shape come to reflect the Marring it had sustained.
The dismayed Valar fled Middle-earth and built up the then-undeveloped continent of Aman. The realm they founded there, Valinor, became even more beautiful than Middle-earth during the Spring of Arda, and the holiness of the Valar kept it nearly free of Arda's Marring. Unfortunately, the removal of the Valar to Valinor also caused them to neglect Middle-earth, which allowed Melkor to further damage it.
 The Destruction of the Two Trees
In Valinor the Valar made the Two Trees, whose Light was pure and uncorrupted. It ennobled those of the Elves who came to dwell in it and learned from the Valar. Nevertheless, even the Eldar had come from Middle-earth and so brought its taint into Valinor with them. The unfortunate death of Míriel, caused by the unnatural failure of her body, resulted from this impurity, as did the jealous response of Fëanor her son to his half-brothers. Physical weakness due to the state of the Earth thus played a part in the disastrous Fall of the Noldor.
Valinor was further visited by the misfortunes characteristic of Arda Marred when Melkor and Ungoliant killed the Two Trees, causing their holy light to be lost forever (save for within the Silmarils, which Melkor stole). Some count the swift decay of Finwë's body after Melkor killed him among the effects of the Marring in Valinor.
 Further Damage
Arda sustained further hurt from the war that the Valar waged soon after the Awakening of the Elves. During this conflict, precipices such as the highlands of Dorthonion were cut into the land, and the Great Sea became much wider and deeper.
The last major alteration of Arda's structure was the Changing of the World, in which Arda was broken and made round, and the Blessed Realm was removed from it. Once Aman and Tol Eressëa were taken from the physical plane, Arda contained no lands that held "the memory of a time without evil".
 Nature of the Marring
The true affliction that the Marring signified went beyond the physical fact of Arda's damage and misshapenness. Morgoth did not only destroy the symmetry of Arda, he also poured out his evil and rebellious will into its very structure. No creature that depended on the natural world for its survival (i.e., all beings aside from the Valar and Maiar) could escape this taint of Morgoth; it inevitably affected their understanding of the world and subsequent actions. Thus, it was the Marring of Arda that allowed misfortunes such as the Shadow to fall upon populations of the Children of Ilúvatar, causing misunderstandings and conflicts among them.
Even after Morgoth himself was removed from Arda, this part of himself that he allowed to pass into its structure remained, and was in fact impossible for anyone save Eru to eradicate fully. The physical matter of Arda was capable of healing itself somewhat if left alone or encouraged to do so by caretakers, and some parts of it were actually less tainted than others (for example, water was held to be purer than land). The degree of corruption an area of the Earth contained often depended on how useful Morgoth believed it to be.
On the other hand, anyone who wished to further Morgoth's designs found in Arda's Marring all sorts of tools with which to do so. Sauron, for example, used gold in forging the One Ring, which turned out to be an optimal metal for creating such an evil object. In most of his works Sauron in fact depended upon the corruption that Morgoth his master had introduced into the world for their success.
In a less tangible fashion, Sauron and many others tended the "evil fruits of Morgoth" by relying upon the confusion and propensity to evil that the Marring could cause among sentient creatures. Sauron, the Deceiver, was particularly skillful at spreading lies among the peoples who chose to trust him.
 Arda Marred and the Children of Ilúvatar
The Marring of Arda of course had many effects both subtle and otherwise upon the Children of Ilúvatar. While most of these effects were adverse in nature, they did in some degree further the designs of Eru, as he himself had declared they would in his speech after the Music of the Ainur.
One important thing the Marring caused was the Waning of the Elves. Because they relied upon the tainted land for food and survival, the bodies of Elves who lived in Middle-earth inevitably became weaker and less substantial over time, until they were little different from wraiths, invisible and immaterial. In this form of existence the Elves could have little effect upon the history of the world, so Men ultimately took their place as the prime dwellers in Middle-earth, as Eru had willed.
The weakness of Men themselves was their relative lack of control over their bodies by their spirits. This allowed the corruption of Morgoth, which existed in the physical aspect of Arda, to enter them much more easily. It is probably this fact which caused Men to be seduced by Morgoth in their early days.
This seduction of Morgoth was especially disastrous because it was theorized that the chief function of Men, in Eru's original design, was for them to undo the Marring and bring about Arda Healed. Men were stripped of this ability upon their Fall and made much weaker and less able to resist the effects of the Marring.
 The Future of Arda Marred
The Elves have always believed that this world is finite and will come to an end, most likely a violent one. However, none of them know when the end of the world will occur. The Second Prophecy of Mandos tells of a great battle in which Túrin will utterly destroy Morgoth, thus avenging Men of the hurt he did to them, but the accuracy of this prophecy is not known. But this prophecy was abandoned by Tolkien.
The Elves also remain in the hope that Eru will make a "new thing and a greater", Arda Healed, after Arda Marred has come to an end. Arda Healed would encompass both the perfection of Arda Unmarred and the rich history of Arda Marred.
Arda's Marring is of course evident throughout all the stories that take place in it. Two accounts in which the nature of the Marring is discussed in detail are that of the Statute of Finwë and Míriel and the Athrabeth Finrod ah Andreth.
The Valarin form of "Arda Marred" is Aþāraphelūn Dušamanūðān. Aþāraphelūn means 'appointed dwelling' (from aþāra, 'appointed', and phelūn, 'dweling') and is the Valarin equivalent of Arda. Dušamanūðān means 'marred'.
 Other Versions of the Legendarium
While Melkor-Morgoth's destructive acts against the physical structure of Arda were always a feature of the Legendarium, the theme of the moral and spiritual corruption with which he imbued the Earth is a relatively late addition. It first appears in notes published in Morgoth's Ring which show the preoccupation Tolkien came to have with the ruinous effects of his "rebellious will".