 This view contrasts with the relational logic of De Morgan, Peirce, Schröder and Russell himself, now standard in predicate logic.Notably, Leibniz also declared space and time to be inherently relational.Although the mathematical notion of function was implicit in trigonometric and logarithmic tables, which existed in his day, Leibniz was the first, in 1692 and 1694, to employ it explicitly, to denote any of several geometric concepts derived from a curve, such as abscissa, ordinate, tangent, chord, and the perpendicular.