Book 19 brings together in its chapters the diversity of ‘things’ and the many distinct tasks and processes they impose on us. At the start of its chapters on numbers, weights, measures and unity, Bartholomew cites The Book of Wisdom on God’s ordering of creation: ‘For it is not said in vain, “You have made all things in number, weight and measure.”’^[113] We see how material ‘things’ involve work in their production, processing and use; their properties have to be taken into account in a practical way. Clothes have to be dyed, pigments ground, food cooked, wax made into candles. Oil has to be put into lamps, milk made into junket, butter, cheese. The chapters on milk inform the reader that it can come from mammals in general and, in particular, from camels, cows, goats, sheep, asses, mares and pigs.^[114] It can be turned into buttermilk, butter, fresh cheese, matured cheese and curds.^[115] This is matter of fact, but the glossator points to the teaching of doctrine (doctrina) as the real subject of the chapters. Like milk, Christian teaching can be sound and nourishing, warm, pure and refreshing, flavoursome, unwholesome and bad, or just right. It can be flavoured or suspect; and like the flow from the teat, the ideas and words of preachers who at first have a lot to say can gradually dry up.^[116] Bartholomew devotes considerable space to eggs and their properties — not only the eggs of birds, but also of ants and spiders, turtles, dragons, toads, locusts, snakes, gryphons, crabs and crocodiles. Eggs can be cooked but may be digestible or indigestible, according to the creatures from which they come.^[117] The glossator shows us that Bartholomew’s odd-seeming lists of eggs, far from being anomalous, can be understood as signifiers of salvation through good works, though not all works are necessarily good. The glosses on eggs include: ‘Take note what the works of just men ought to be like; concerning the fertile soil of grace and devotion; how vainglory destroys works.’^[118] Doves' eggs can signify the works of the simple and good; eagles' eggs those of the powerful, and also Christ in the heart; dragons’ eggs, however, are a warning of those with power and hidden malice; spiders' eggs signify the lazy works of hypocrites and heretics, and the eggs of ants are like those of the poor.^[119] While it seems safe to conclude from the annotations that the chapters on milk, eggs, honey and wax could hold spiritual and liturgical associations, it is not possible here to fully unravel the symbolic causes, conditions and effects of the other material items mentioned in Book 19.

The chapters on tastes, aromas and foods should remind us that this was a literary culture in which Hugh of St Victor and Bernard of Clairvaux had portrayed reading as chewing, tasting and swallowing for the replenishment of the soul.^[120] Bartholomew makes palatable doctrines that were complex, controversial and highly scholastic. The term 'accident', for example, had a far-from-casual philosophical meaning which, in the context of contemporary debate about the transformation of matter, Thomas Aquinas (1225–74) expounded in the articles of his Summa Theologica. Chapters in Book 19 treat materials which, like the Eucharist, involve changes: butter, cheese, curds and whey are all essentially milk; honey, mead, candle-wax are all essentially that which bees make. There is also a chapter on change itself: ‘On coagulation’. Spiced and sweetened wines are still essentially wine. It is surely no accident that Bartholomew reiterates examples of the transformation of matter at a time when the relationship between a thing’s inner substance, or substancia, and its outer appearance, or species, was a highly important issue for the church.^[121] For Bartholomew, writing when Aristotelian philosophy appeared to be at odds with the church’s teaching and when the nature of transubstantiation was the subject of much debate, the ‘appearance of those things which are of frequent use’ and their physical properties were important and controversial.^[122] Beneath appearances and properties lay the possibility of a conversion to something useful and even divine. In Book 19’s accounts of the conversion of milk into butter, junket and cheese; of beeswax into candles; of honey and wines into medicines, we may justifiably infer an allusion to the spiritual transformation believed to be effected at the Mass.