Do there exist many worlds, or is there but a single world? This is one of the most noble and exalted questions in the study of Nature. - Albertus Magnus

This dumb ox will fill the world with his bellowing.

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.

Natural science does not consist in ratifying what others have said, but in seeking the causes of phenomena.