By the thirteenth century chestnuts had become an established article of human food in Italy. Pietro Crescenzi (1230-1307) describes two varieties, the cultivated and the wild, and quotes the Arabian physician Avicenna to the effect that chestnuts are "di tarda digestione ma di buono nuttimento." It is perhaps for this very reason that chestnut bread is acceptable to those engaged in heavy labor. Fynes Moryson says in his _Itinerary_ (1617) that maslin bread made of a mixture of rye and wheat flour was used by labourers in England because it "abode longer in the stomach and was not so soon digested with their labour." Crescenzi, who was a lawyer and a judge, says in his preface that he had left his native Bologna because of the civil strifes, had taken foreign service in several parts of Italy, and so had opportunity to see the world. He wrote his book on agriculture because, as he says, of all the things he learned on his travels there was nothing "piu a bondevole, niuna piu dolce, et niuna piu degna de l'huomo libero," a sentiment which Socrates had expressed sixteen hundred years earlier and which was echoed six hundred years later by another far-sighted Italian, the statesman Cavour.] [Footnote 62: The white chalk which Scrofa saw used as manure in Transalpine Gaul, when he was serving in the army under Julius Caesar, was undoubtedly marl, the use of which in that region as in Britain was subsequently noted by Pliny (H.N. XVII, 4). There were no deposits of marl in Italy, and so the Romans knew nothing of its use, from experience, but Pliny's treatment of the subject shows a sound source of information. In England, where several kinds of marl are found in quantities, its use was probably never discontinued after the Roman times. Walter of Henley discusses its use in the thirteenth century, and Sir Anthony Fitzherbert continues the discussion in the sixteenth century. In connection with the history of the use of marl in agriculture may be cited the tender tribute which Arthur Young recorded on the tombstone of his wife in Bradfield Church. The lady's chief virtue appears to have been, in the memory of her husband, that she was "the great-grand-daughter of John Allen, esq. of Lyng House in the County of Norfolk, the first person according to the Comte de Boulainvilliers, who there used marl."