A detailed woodcut headpiece contains an oval vignette of a landscape with a tree and architectural ruins, surrounded by decorative scrolls and a banner reading "From here and there" original: "HINC INDE".

RATIONAL

PSYCHOLOGY:

PROLEGOMENA.

§. 1.

The definition of rational psychology.

A decorative drop cap initial 'P' features a tree on a pedestal within a landscape. Rational psychology is the science of those things which are possible through the human soul.
We gave this definition of Psychology as a branch of philosophy in the Preliminary Discourse Wolff refers to his "Discursus praeliminaris de philosophia in genere," which prefaced his 1728 work on Logic. (§. 58), and we advised that it is suitable for distinguishing rational psychology from empirical psychology (§. 122. Prelim. Disc.).

§. 2.

Why there is a place for demonstration in Rational Psychology.

Since Rational Psychology is a science (§. 1), and science indeed consists in the habit of demonstrating original: "habitu demonstrandi." In Wolff’s system, science is not just a collection of facts, but the intellectual ability to prove every assertion from first principles. what we affirm or deny (594. Logic); Those things which are treated in Rational Psychology must be demonstrated.