He made himself master of Oughtred's "Clavis Mathematica" in his old age, according to Aubrey, who found him "perusing it and working problems not long before he dyed."
"Fathers of Biology"
Charles McRae
264. "The Clavis of St. Melito, who was bishop of Sardis, it is said, in the beginning of the second century, consists of a catalogue of many hundreds of birds, beasts, plants, and minerals that were symbolical of Christian virtues, doctrines, and personages."
"Christian Mysticism"
William Ralph Inge
There is a Clavis appended, also stated to be "published at his Majesties command."
"The Mystery of Francis Bacon"
William T. Smedley