Alchemy: "Alchemy was both an empirical art, which sought to transmute base metals into gold (or other precious metals), and the theoretical science that explained and guided this effort. . . . Aristotle's natural philosophy offered an explanation of this unity, portraying the four elements as a product of prime matter and pairs of the four elemental qualities: hot, cold, wet, dry. Alter the qualities, and you transmute the elements one into another. Alter the proportions of the elements in a mixtum, and you transform the mixtum into a different substance (Lindberg, 1992)." Pages 287-288

Astrolabe: An Arabic medieval instrument invented to measure and predict the positions of the sun and major stars.

Eccentrics: A deviation from circularity in a planetary orbit.

Efficient Cause: Aristotelian philosophy includes four forms of causation: formal cause "the form received by a thing," material cause "the matter underlying that form, which persists through the change," efficient cause "the agency that brings about the change", and final cause "the purpose served by the change" (Lindberg, 1992). Page 53

Entity: In Aristotelian and medieval philosophy entities include all of the different categories in metaphysics that are needed to explain the types of being.

Epicycles: Ptolemaic cosmology includes a smaller circular planetary motion as well as a larger circular orbit around the Earth. Epicycles are used to correct for discrepancies between observed planetary positions and the theoretical positions required for a simple circular orbit.

Heliocentric: A model of the solar system in which the sun is at the center and the planets orbit around the sun (as opposed to geocentric or Ptolemaic in which the earth is the center of the solar system and the planets orbit around the earth.)

Metaphysics: A branch of philosophy that concentrates on the nature of reality and being.

Nominalism: A theory that denies the existence of a separate universal entity that encompases the qualities of individual entities. For example, there is not a universal concept of trees or treeness, reality only includes individual trees.

Ockham's Razor: In modern science, Ockham's razor looks for explanations that require the least number of assumptions or steps. It is related to the medieval idea of parsimony, which attempts to reduce the number of metaphysical entities.

Paradigm: "A paradigm is an accepted model or pattern, . . . Paradigms gain their status because they are more successful than their competitors in solving a few problems that the group of practitioners has come to recognize as acute. To be more successful is not, however, to be either completely successful with a single problem or notably successful with any large number" (Kuhn, 1996). Page 23