the astringent part being dissolved renders the juice austere, it being the property of a watery fluid to obtund the powers of every juice. If a subtile and airy fluid be superadded, it will become acid, for coldness being attenuating will render the former quality acid. When moistened and heated at the same time, if with a watery humidity, it will occasion a change to sweetness; but if with an airy, to fatness; for the fruits of such trees as appear sweet to us when ripened, are, when newly formed, sour and dry in their consistence, each according to the nature of the tree which produced it; but in process of time, they become more humid or juicy; and some get acidity superadded to their sourness, which latter quality when they have laid aside they become again sweet as they arrive at maturity. Some do not acquire sweetness at all while upon the trees, but after a time, when separated from them. Some without the intermediate acidity pass from sourness to sweetness, as the fruit of the olive. All things are concocted by heat, which is of a twofold nature, the one proper and innate, and the other supplied from without by the sun. But, since being sour at first, they become sweet when ripe, their sweetness is occasioned by heat; but their acidity and sourness by cold. And it has already become obvious that as fruits being sour at first, in process of time become, some sweet, some acid, some austere, and some remain sour, that great variety will arise from a mixture of these qualities. Wherefore, the fruit of the ilex, the cornel, and other such things, are sour to the last, because they remain cold and dry as at the beginning, being only increased in size, but acquiring no other internal change. The fruits of the myrtle, the wild pear, and the oak are sweet and sour at the same time; but the fruit of Aminæan vines, wine, and such like things, are only austere. The fruit of the palm tree, and of wines, the Surrentine, and such as have sweetness joined to astringency, are at the same time austere and sweet. The Theræan wine, the Scybelitic, boiled must called rob, and other such like things, are only sweet. The fruit and juice of the olive in particular, but also of all other such things from which oil is formed, are fatty. And as a sour juice in process of time, becoming at first sweeter, and afterward turning more acrid and bitter, ends in becoming wholly bitter; so in like manner, a cold juice becomes at first more acid, and if wholly congealed it turns entirely acid; and such fruits as at gathering are filled with much humidity, and such as otherwise acquire much water, readily become acid from very slight causes. For if the unripe grape is acid, but the ripe sweet, and if all fruits are ripened by the solar heat, it is obvious that what is more imperfect and colder is acid; whereas, what is more perfect and hotter is sweet. When wine, therefore, from refrigeration becomes acid, it is clear that it returns again to the same juice from which