Dian Cécht, A Compendium of the Ancient Gods

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Dian Cécht was the physician of the Tuatha Dé Danann, the divine race who occupied Ireland in the heroic age, and his skill in healing was such that no wound could resist his ministrations. When King Nuada of the Tuatha lost his arm in the First Battle of Mag Tuired, Dian Cécht made for him an arm of silver, and Nuada was thereafter called Nuada Argetlam, Nuada of the Silver Hand. But the rule of the Tuatha required a king physically perfect, and Nuada had to step down from his kingship while the silver arm was upon him.

Dian Cécht's son Miach surpassed his father; for Miach worked further upon the silver arm, growing flesh over it joint by joint, until in nine days the arm was as good as the original. When Dian Cécht saw what his son had done, he was overcome by jealousy. He struck Miach three times with his sword, and each time Miach healed himself; on the fourth blow, Dian Cécht struck through to the brain, and Miach died. From his grave grew three hundred and sixty-five herbs, each marking the joint or organ they would heal. Miach's sister Airmed gathered them and arranged them upon her cloak according to the part they cured; but Dian Cécht, in further jealousy, came and overturned the cloak and mixed the herbs together. So the perfect knowledge of healing was lost forever, and the herbs that men know by their virtues are only the few that Airmed had remembered before her father's malice undid her work.

Dian Cécht presided also over the Well of Slaine — the Well of Health — into which the wounded warriors of the Tuatha were thrown after each day's fighting in the Second Battle of Mag Tuired, that they might be healed and ride out again the next morning. The well was a great resource of the Tuatha and a chief reason their losses in battle were so much less than their enemies'.

Curator’s note

What the sources say, and what later tradition added. The sources for this bay

Dian Cécht and his family are described in Cath Maige Tuired ("The Battle of Mag Tuired"), the great Old Irish saga of the conflict between the Tuatha Dé Danann and the Fomoiri; the text survives in a sixteenth-century manuscript but is much older, perhaps tenth- or eleventh-century in its present form, with even older oral roots. The Lebor Gabála Érenn ("Book of Invasions") gives further genealogical material. Airmed and Miach are essentially Dian Cécht's two children whose careers (and deaths) limit his own; the tale has been read as an etiology of the limits of medical knowledge — why we cannot heal everything, why the herbs we know are only an imperfect handful of what could be known.

Kin in the sources

Each tie is quoted from the entry that states it.

Parent ofAirmedAirmed and Miach are essentially Dian Cécht's two children

When the sources speak

Dated witnesses for The Celtic Mythologies. A date marks when the evidence was written down, not when the belief began. The whole timeline

2nd–1st millennia BCE: Indo-European language dispersals and regional Bronze Age cultures provide a remote comparative background, not a recoverable common canon.
c. 500 BCE–1 CE: Iron Age material culture, names, sanctuaries, and classical ethnography offer early but external evidence for Celtic and Germanic religions.
1st–4th centuries CE: Roman inscriptions and provincial cults preserve many Celtic, Germanic, and local divine names.
4th–8th centuries CE: Migration-period and early medieval conversion transform ritual institutions while heroic traditions continue.
8th–11th centuries CE: Viking Age poetry, runic evidence, archaeology, and Scandinavian conversion form the core context of Norse myth.
9th–12th centuries CE: Slavic, Baltic, and Finnic traditions enter chronicles and missionary accounts, often through hostile observers.
11th–14th centuries CE: Irish, Welsh, and Icelandic manuscripts preserve major narrative corpora in Christian literary environments.
12th–16th centuries CE: Saxo, saga compilers, Baltic chroniclers, and later antiquarians systematize or reinterpret older material.