n 1805, by the treatise
_Knowledge, Faith, and Presentiment_. Besides these he composed a _Handbook
of Psychical Anthropology_, 1821 (2d ed., 1837 _seq_.), text-books of
Logic, Metaphysics, the Mathematical Philosophy of Nature, and Practical
Philosophy and the Philosophy of Religion, and a philosophical novel,
_Julius and Evagoras, or the Beauty of the Soul_.

Fries adopts and popularizes Kant's results, while he rejects Kant's
method. With Reinhold and Fichte, he thinks "transcendental prejudice" has
forced its way into philosophy, a phase of thought for which Kant himself
was responsible by his anxiety to demonstrate everything. That _a priori_
forms of knowledge exist cannot be proved by speculation, but only by
empirical methods, and discovered by inner observation; they are
given facts of reason, of which we become conscious by reflection or
psychological analysis. The _a priori_ element cannot be demonstrated nor
deduced, but only shown actually present. The question at issue[1] between
Fries and the idealistic school therefore becomes, Is the discovery of the
_a priori_ element itself a cognition _a priori_ or _a posteriori_? Is
the criticism of reason a metaphysical or an empirical, that is, an
anthropological inquiry? Herbart decides with the idealists: "All concepts
through which we think our faculty of knowledge are themselves metaphysical
concepts" (_Lehrbuch zur Einleitung_, p. 231). Fries decides: The criticism
of reason is an empirico-psychological inquiry, as in general empirical
psychology forms the basis of all philosophy.

[Footnote 1: Cf. Kuno Fischer's Pro-Rectoral Address, _Die beiden
Kantischen Schulen in Jena_, 1862.]

With the exception of this divergence in method Fries accepts Kant's
results almost unchanged, unless we must call the leveling down which they
suffer at his hands a considerable alteration. Only the doctrine of the
Ideas and of the knowledge of reason is transformed by the introduction and
systematization of Jacobi's principle of the immediate evidence of faith.
Reason, the faculty of Ideas, _i.e._, of the indemonstrable yet indubitable
principles, is fully the peer of the sensibility and the understanding. The
same subjective necessity which guarantees to us the objective reality of
the intuitions and the categories accompanies the Ideas as well; the faith
which reveals to us the _per se_ of things is no less certain than the
knowledge of phenomena. The ideal view of the world