Cicero, Cato Maior 22 = T 81 Radt
Sophocles ad summam senectutem tragoedias fecit. quod propter studium cum rem neglegere familiarem videretur, a filiis in iudicium vocatus est, ut quem ad modum nostro more male rem gerentibus patribus bonis interdici solet, sic illum quasi desipientem a re familiari removerent iudices. Tum senex dicitur eam fabulam quam in manibus habebat et proxime scripserat, Oedipum Coloneum, recitasse iudicibus quaesisseque num illud carmen desipientis videretur. Quo recitato sententiis iudicum est liberatur.
Sophocles composed tragedies right up to extreme old age. And when, on account of his zeal, he seemed to be neglecting his property, he was summoned to court by his sons, so that, just as it is our custom for good fathers to be indicted for negligence in administering their property, so the judges were to remove his control of the property on the grounds that he had dementia. At that point the old man is said to have recited to the judges a tragedy of his which was then in preparation and which he had most recently written, the Oedipus at Colonus, and to have asked whether it seemed to be the poem of someone suffering from dementia. After this recitation, he was set free by the verdict of the judges.