Speculum mundi. Or, A glass representing the face of the world [electronic resource] : Shewing both that it did begin, and must also end: the manner how, and time when, being largely examined. The whole of which, may be fitly called an hexameron. Or a discourse of the causes, continuance, and qualities of things in nature; occasioned as matter pertinent to the work done in the six days of the world's creation. The fourth edition, much beautified and enlarged, by John Swan.