Permanent Quotes - page 16
The metals are all essentially identical; they differ only in form. Now, the form brings out accidental causes, which the experimenter must try to discover and remove, as far as possible. Accidental causes impede the regular union of sulphur and mercury; for every metal is a combination of sulphur and mercury. A diseased womb may give birth to a weakly, leprous child, although the seed was good; the same is true of the metals which are generated in the bowels of the earth, which is a womb for them; any cause whatever, or local trouble, may produce an imperfect metal. When pure sulphur comes in contact with pure mercury, after more or less time, and by the permanent action of nature, gold is produced.
Albertus Magnus
Agriculture is the art of deriving from the earth the most valuable organic productions. He who exercises this art, seeks to obtain profit by causing to grow, and by using, its animal and vegetable productions. The more considerable the gain derived, therefore, the better is the object accomplished. The most perfect agriculture is, evidently, that which produces, by the application of labour, the largest and the most permanent profit in comparison with the means employed. Systematic agriculture ought, then, to teach us all the circumstances by means of which we may derive the most considerable profit by the practice of the art.
Albrecht Thaer