Nadir Nadir The nadir (, ; from / ALA-LC: "naẓīr", meaning "counterpart") is the direction pointing directly "below" a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface there. Since the concept of "being below" is itself somewhat vague, scientists define the nadir in more rigorous terms. Specifically, in astronomy, geophysics and related sciences (e.g., meteorology), the nadir at a given point is the local vertical direction pointing in the direction of the force of gravity at that location. The direction opposite the nadir is the zenith. Nadir is
Preliminary Discourse to the Encyclopedia of Diderot reflection or reason, which is the basis of Philosophy; and what d'Alembert refers to as "imagination," (50) or imitation of Nature, which produces Fine Arts. From these divisions spring smaller subdivisions such as physics, poetry, music and many others. d'Alembert was also greatly influenced by the Cartesian principle of simplicity. In this first part of the book, he describes how the reduction of the principles of a certain science gives them scope and makes them more "fertile" (22). Only by reducing principles can they be understood and related to each other. Ultimately, from a high "vantage point" (47) the philosopher