If we take an unprejudiced view of the processes of consciousness, free from all the so-called association rules and theories, we see at once that an idea is no more an even relatively constant thing than is a feeling or emotion or volitional process. There exist only changing and transient ideational processes ; there are no permanent ideas that return again and disappear again.

The results of ethnic psychology constitute, at the same time, our chief source of information regarding the general psychology of the complex mental processes.

The distinguishing characteristics of mind are of a subjective sort; we know them only from the contents of our own consciousness.

Our mind is so fortunately equipped, that it brings us the most important bases for our thoughts without our having the least knowledge of this work of elaboration. Only the results of it become unconscious.

Hence, even in the domain of natural science the aid of the experimental method becomes indispensable whenever the problem set is the analysis of transient and impermanent phenomena, and not merely the observation of persistent and relatively constant objects.

Physiology seeks to derive the processes in our own nervous system from general physical forces, without considering whether these processes are or are not accompanied by processes of consciousness.

There are other sources of psychological knowledge, which become accessible at the very point where the experimental method fails us.