It would not be easy to miss the meaning of this mistake. Michael Scot had probably written or translated a treatise on algebra. We may remember how well such a conjecture agrees with the tone of Pisano’s dedicatory letter to him, in which he submitted the _Liber Abbaci_ to Scot’s revision, and acknowledged him as a supreme master in this branch of science. It is difficult to account for this fame save by supposing the existence of an unknown work by Michael Scot on the veritable Almuchabola, of which this pretended treatise on magic is all that now survives. The mistake that gave it so corrupted a form could hardly have been made as late as the seventeenth century, when such things were well understood. The manuscript, though dating from that time, is probably only a copy of one much older. The preface, indeed, mentions the year 1255 as the epoch of translation, and, although Michael Scot had then lain more than twenty years in his grave, this date would suit well as the birth-hour of a legend which, though certainly later than Scot’s own day, had yet made considerable progress in the popular mind before the close of the century. This explanation of the matter receives some indirect support from a remark of Bacon’s. ‘It is to be noticed,’ he says, ‘that many books are taken for magical works which are in reality nothing of the kind, but contain true and worthy wisdom.’[278] He adds that there are several ways of concealing one’s doctrine from the vulgar, such as the use of Hebrew, Syriac, and Arabic characters, and the _Ars Notoria_ or shorthand. There is much reason to think it was in this very way that Michael Scot had suffered. A mistake like that indicated by Bacon was probably the real origin of his mysterious reputation as a magician.