2. Study of causal relationships.

3. Establishment of the principles of psychic activity.

The subject-matter will be drawn on the one hand, from that
already presented by psychological science, but will be treated
throughout from the point of view of the criminal judge, and prepared
for his purposes. On the other hand, the material will be
drawn from these observations that alone the criminologist at work
can make, and on this the principles of psychology will be brought
to bear.

We shall not espouse either pietism, scepticism, or criticism.
We have merely to consider the individual phenomena, as they may
concern the criminalist; to examine them and to establish whatever
value the material may have for him; what portions may be of
use to him in the interest of discovering the truth; and where the
dangers may lurk that menace him. And just as we are aware
that the comprehension of the fundamental concepts of the exact
sciences is not to be derived from their methodology, so we must
keep clearly in mind that the truth which we criminalists have to
attain can not be constructed out of the _formal_ correctness of the
content presented us. We are in duty bound to render it _materially_
correct. But that is to be achieved only if we are acquainted with
principles of psychology, and know how to make them serve our
purposes. For our problem, the oft-quoted epigram of Bailey's,