The practice of physic was hereditary in certain  families, and each of the nobles had a special physician attached to his service. In the more ancient  times, medical knowledge was handed down by oral tradition from father to son; then, as learning advanced, by written books, carefully preserved in each family. The sons were generally educated by their fathers in the practice of physic, but it is said that Dianecht, being jealous of the superior skill of his son, caused him to be slain, when from, the grave of the youth sprang a number of herbs, all efficacious in curing disease; and thus, though, dead, he carried on his work.
After the introduction of Christianity by St. Patrick, schools were established both for law; and physic, where Latin was sedulously taught and freely spoken. Camden describes these schools, and says of them: They speak Latin there like the  vulgar tongue, conning by rote the aphorisms of Hippocrates, Galen, Avicenna, and others amongst the great masters of surgery.

Ancient Medical Manuscripts.

Numerous copies of these ancient writers were made by the learned doctors and freely distributed
amongst the profession, so that many of the manuscripts can still be found in the chief libraries of Europe. They are written on vellum, and are  beautiful specimens of penmanship. A commentary in Irish was sometimes added, besides which, several translations into Irish of the chief medical works whole and entire, are in existence.
In proof of the great and accurate knowledge of these Irish physicians, it is stated by Sir William Wilde, that when preparing "The Status of Diseased from the Earliest Times," for the Irish census, he was able to tabulate seventy-five fatal diseases accurately described by the native doctors, with many that were not fatal; and he asserts that the Irish terms for the principal diseases were of far more appropriate significance than those at present employed in English, or derived from the Latin and Greek.

Druidic Charms

Meantime, the ancient Druidic charms and in vocations continued to hold their power over the people, who believed in them with undoubting faith. No doubt, in pagan times, the invocations were made in the names of Baal and Ashtaroth,   and by the power of the sun, the moon, and the winds; but the Christian converts, while still retaining the form of the ancient charms, substituted the names of the Trinity and the words of the Christian Ritual as still more powerful in effecting cures. And in this mode they are used to the present day amongst the peasants, who consider them as talismans of magic power when said over the sick; and no amount of argument would shake their faith in these mystic formulas which have come down to them through centuries of tradition; nor would any one venture to laugh at them, or an evil fate would certainly fall on the scorner. For, above all things, fervent faith is necessary while the mystic words are uttered, for the charm will not work for good; and charms are set with most effect upon Wednesdays and Fridays, and must be set fasting, generally before sunset.

Ancient Cures, Charms and Usages of Ireland

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