The Ways of Harming are Easy. The Ways of Healing are Hard.
Before their arrival in Ireland the Tuatha Dé Danann were said to have traveled far and wide, learning all manner of skill, druidry and other occult practices. The power of this tribe was such that their movements were noted in visions of prophecy long before their ships ever graced the skies.
One of the most influential characters in the Tuath was called Dian Cecht and he was said to possess the greatest skills in the ways of healing and restoration.
When battle came against the Tuatha Dé Danann, Dian Cecht was never far away. It was said that he could set up a healing well, and a warrior laid within it's herb infused waters, would arise with all but the most mortal of would healed. These warriors would return to the battlefield the next day as if no harm had come to them and this was how the tribe sustained their battles for weeks at a time.
The skill and renown of Dian Cecht's healing waters was such that during the invasion known as the second battle of Moytura, the Fomorian foes knew that they would not stand a chance if the well remained open to the healers. So it was that with guile and stealth a number of their warriors entered the camp of the Tuatha Dé Danann, not armed for battle, but each carrying a stone. These were placed into the healing waters until the entire bath was filled so that no more water could flow. So it was that the Fomorian's destroyed the healing magics of Dian Cecht and lessened the power of the Tuatha Dé Dannan for their battling.
Yet, no stranger to the ways of harming is Dian Cecht, for it was said that he could cause the most mortal wounds to fall from his sword and that none but he, or one of skill matching his, could survive them. The most unfortunate display of his knowledge of harming comes against his own son. Miach had managed a feat in healing that even Dian Cecht could not rival, in restoring to Nuada his own arm, regenerated and whole from whence it has been buried and decayed.
In a wrath Dian Cecht took up his sword and placed many mortal wounds upon Miach, each of which the lad healed with his skill. Wounds which should have ended even the mightiest warrior, were restored in all but an instant by Miach's knowledge of the healing arts. As such Dian Cecht took his harming to the furthest extent and smote Miach's brain from his skull. Taking the brain away ensured that his son could not restore himself and so he was buried. Yet Miach had one last healing gift to give, for upon his grave grew every healing herb, matched to the location of the body that it would restore.
It might be fair to say that anyone can cause hurt or harm to fall upon those around them, but only those who know the harming of a thing can truly understand the healing of it. When it comes to Dian Cecht - The Ways of Harming are Easy. The Ways of Healing are Hard.