Cosmas and Damian seem to be the last saints included in the list of the communicantes of the Mass, in the 1st half of the 6th c. Kennedy 191-193. Unknown by the Depositio martyrum of 354, they are known to the Mart. hier. and to the Gelasian and Gregorian sacramentaries, on 27 September. Their fame spread quickly beyond the Urbe. In the 6th c. they are present in the mosaics of S. Michele at Ravenna; Gregory of Tours attests their fame in Gaul, calling them twins, doctors and martyrs In gloria martyrum 94. Aldhelm, between the 7th and 8th c., Bede, Usuard and Adone mention them in their martyrologies Giannarelli 52-53. Known from Sicily to all of France, from Germany to Spain, they became the patrons of doctors, surgeons, pharmacists and of those who practiced even minor medicine. They specialized in the healing of plague, dropsy and kidney illnesses and were also the object of legendae novae see Bartholomew of Trent, Passionale de sanctis 85 and the Legenda aurea of Jacobus de Voragine. At Florence in the 15th c. they held a unique position as patrons of the Medici family, protagonists of a political-cultural project that assured the saints a strong presence in the figurative arts of Humanism and the Renaissance see Novembri, Sebregondi, Dillon Bussi, with a new flourishing of stories linked to their lives and miracles.