[Sidenote: Adelard and alchemy.] Adelard was interested in alchemy as well as astrology and magic, if the attribution to him in a thirteenth century manuscript[40] of the twelfth century version of the _Mappe clavicula_ is correct. We have seen that the original version of that work was much older than Adelard’s time, but he perhaps made additions to it, or translated a fuller Arabic version. The occurrence of some Arabic and English words in certain chapters of the later copies are perhaps signs of his contributions. Berthelot, however, thought that few of the new items in the twelfth century version originated with Adelard and that many of the additions were taken by him, or by whoever was responsible for the later version, from Greek rather than Arabic sources.[41] [Sidenote: Importance of the _Natural Questions_.] Our attention will be devoted chiefly to the two treatises by Adelard which we have already mentioned as the most original of his works. Of these the _Natural Questions_ are evidently much more important than the _De eodem et diverso_, which is largely taken up with a justification, in the style of allegorical personification made so popular by Martianus Capella and Boethius, and with much use of Plato’s _Timaeus_, of the seven liberal arts against the five worldly interests of wealth, power, ambition, dignities, and pleasure. The _Natural Questions_, although put into a dramatic dialogue form somewhat reminiscent of Plato, deal without much persiflage with a number of concrete problems of natural science to which definite answers are attempted. [Sidenote: Occasion of writing.]