PROLEGOMENA TO PSYCHOLOGY

[the reason] is given for those things which are within the soul, or which have the potential to be there (§. 4). Because of this, the propositions within this science become determinate In Wolff’s logic, a "determinate" proposition is one where the subject and predicate are so clearly defined that their relationship can be used for further rigorous deduction. (§. 320, Logic), and are consequently fit for reasoning (§. 499, Logic). Therefore, since through the art of discovery artem inveniendi: the systematic method of uncovering new truths through logical deduction rather than just sensory experience other unknown truths are gathered from known, determinate propositions (§. 461, Empirical Psychology), things now become known about the soul which it was not possible to detect a posteriori Latin: a posteriori—knowledge derived from experience or sensory observation; "after the fact.". Rational Psychology, therefore, reveals things about the soul that would have been inaccessible to observation alone.

Indeed, since through Rational Psychology our acuity in observing those things which are in the soul is also increased (§. 8), it can happen that things detected a priori Latin: a priori—knowledge derived from pure reason or definition, independent of specific experiences; "from the beginning." in the Rational [Psychology] may now also lie open to observation once they have been clearly perceived by us. For we find through experience that things already perceived by us are more easily observed than those which are completely unknown; nevertheless, it cannot be denied on this account that psychological knowledge is enriched by the benefit of Rational Psychology. On the contrary, if anyone wishes to compare what we shall deliver in the following pages with those things we have presented in Empirical Psychology, he will have the evidence of his own eyes original: "oculatam habebit fidem," literally "he will have eye-witness faith" or "certainty through his own sight.".

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OF THE PROLEGOMENA.

A decorative woodcut tailpiece features a central pomegranate bursting with seeds, surrounded by a symmetrical arrangement of leaves, floral blossoms, and other fruits like pears or citrus. In the 18th century, such ornaments often symbolized the "fruitfulness" of the knowledge contained within the book.