Page:The Works of Aristotle - Vol. 6 - Opuscula (1913).djvu/119

Rh blue-grey, and neither their leaves nor their fruits decay; for trees in which this occurs have a great quantity of heat and rarefied water in their lower reservoirs. Thus as the year goes on this water will retain its heat on account of the coldness of the air; and because the heat goes out to the cold, it carries the moisture out with it, and the moisture tinctures it with the natural colour of heat, and therefore the colour is seen in the appearance of the tree. Consequently cold and heat are converted into activity, and the moisture retains heat, and therefore another colour makes its appearance.

will be bitter because the heat and moisture have not completed the process of assimilation (cold and dryness hindering the completion of this process), and so fruit turns bitter. This can be illustrated by the fact that what is bitter, when put into fire, becomes sweet. Trees which grow in sour water produce sweet fruit, because the sourness assisted by the heat of the sun attracts that which is of its own quality, namely, cold and dryness. Sweet liquids therefore make their appearance inside the tree, and the innermost part of the tree becomes hot when the sun shines continuously above it, and the flavour of the fruit will be successively sour, and then, when the process of assimilation has taken place, the sourness will be gradually dissolved until it disappears, and sweetness will make its appearance. Consequently the fruit will be sweet, while the leaves and extremities of the tree will be acid. When the maturation is complete, the fruit will be bitter: this is due to a superfluity of heat with very little moisture. The moisture is used up and the fruit makes the heat rise, and so the fruit will be bitter, and the stones in the fruit will be pyramidal in form on account of the upward attraction of the heat and the downward attraction of the cold and moisture which are of the same nature as sour water; and the moisture remains in the trunk of the tree, which consequently thickens, while its extremities are thin. If trees are planted in temperate soil, they reach maturity quickly before the days