"With us there was a doctor of phisike; In al the world, was thar non hym lyk To speke of physik and of surgerye, For he wos groundit in astronomie. He kept his pacient a ful gret del In hourys by his magyk naturel; Wel couth he fortunen the ascendent Of his ymagys for his pacient." Fosbrooke has divided talismans into five classes, examples of some of which I have already given. They are: "1. The _astronomical_, with celestial signs and intelligible characters. 2. The _magical_, with extraordinary figures, superstitious words, and names of unknown angels. 3. The _mixed_, of celestial signs and barbarous words, but not superstitious, or with names of angels. 4. The _sigilla planetarum_, composed of Hebrew numeral letters, used by astrologers and fortune-tellers. 5. _Hebrew names and characters_. These were formed according to the cabalistic art." The doctrine of signatures bears a close resemblance to talismans, and some believe that talismans have largely grown out of this doctrine. Dr. Paris[79] defines the doctrine as the belief that "every natural substance which possesses any medical virtues indicates, by an obvious and well-marked external character, the disease for which it is a remedy or the object for which it should be employed." Southey says,[80] "The signatures [were] the books out of which the ancients first learned the virtues of herbs--Nature having stamped on divers of them legible characters to discover their uses." Some opined that the external marks were impressed by planetary influences, hence their connection with talismans; others simply reasoned it out that the Almighty must have placed a sign on the various means which he had provided for curing diseases. Color and shape were the two principal factors in interpreting the signatures. White was regarded as cold and red as hot, hence cold and hot qualities were attributed to different medicines of these colors respectively. Serious errors in practice resulted from this opinion. Red flowers were given for disorders of the sanguiferous system; the petals of the red rose, especially, bear the "signature" of the blood, and blood-root, on account of its red juice, was much prescribed for the blood. Celandine, having yellow juice, the yellow drug, turmeric, the roots of rhubarb, the flowers of saffron, and other yellow substances were given in jaundice; red flannel, looking like blood, cures blood taints, and therefore rheumatism, even to this day, although many do not know why _red_ flannel is so efficacious.