Wilhelm Wundt, answered from the texts and cited to the page.
Psychology is the science of immediate experience — of the world not as the physicist abstracts it from the observer, but as it is actually given to a conscious being living through it. The immediate contents of that experience are, under all circumstances, processes of a composite character: sense-perceptions, memories, feelings, emotions, volitional acts, all continually united in the most various ways, each of them itself a more or less composite whole.1
Scientific investigation of such material faces three problems in succession: the analysis of composite processes into their elements; the demonstration of the combinations those elements enter into; and the investigation of the laws operative in the formation of such combinations.2 The method proper to the simpler processes is experimental introspection — not the loose self-inspection of the old philosophers, who excited complicated thought-processes directly and without preparation and then asked their subjects to report on them, discovering nothing, and ending ultimately back at scholastic philosophy.3
The rule valid for psychology as for any other science is that we cannot understand the complex phenomena before we have become familiar with the simple ones; and the general phenomena of simple processes in consciousness — the combination and comparison of rows of beats, the facts of attention, the scope of consciousness — give us the most general preliminary conditions that must serve as criterion for the more complicated processes.4
But the laboratory has a boundary. The higher mental life — language, thought, art, the development of concepts across peoples — cannot be brought under experimental control and must be studied through its products. The word, for instance, is the real ideational equivalent for the concept that cannot be formed into a direct idea; it changes abstract thoughts into concrete ideational processes that can be heard and seen.5
And the creations of art are no less thought-compounds than those of science, following the same laws of apperception: the artist grasps the whole of a work in its outlines before carrying out any of the parts, while a total idea forms and exerts a reciprocal influence upon the original.6 These higher productions of the collective mind require the historical and comparative method — what I called Völkerpsychologie — standing alongside the experimental science of the elementary individual mind as its necessary other half.
Physiological psychology itself ends, finally, with the questions of the nature of the mind and of the relation of consciousness to an external world — the questions with which the philosophical psychology of an older day was wont to begin — and with a characterisation of the general attitude psychology must take when it seeks to trace the laws of the mental life as manifested in history and in society.7
That is the full scope of what I set out to study: from the simplest sensation to the highest collective mental product.
Sense-perceptions of external objects, memories of such sense-perceptions, feelings, emotions, and volitional acts, are not only continually united in the most various ways, but each of these processes is itself a more or less composite whole.Outlines of Psychology
The first is the analysis of composite processes; the second is the demonstration of the combinations into which the elements discovered by analysis enter; the third is the investigation of the laws that are operative in the formation of such combinations.Outlines of Psychology
It is obvious to the reader, who has followed our discussion so far, that nothing can be discovered in such experiments, where the most complicated psychical processes are investigated directly and without any further preparation... This alleged method of exact introspection ended ultimately at the point from whence it started, i.e. the scholastic philosophy.An Introduction to Psychology
the rule, valid for psychology as well as for any other science, that we cannot understand the complex phenomena, before we have become familiar with the simple ones... the general phenomena of the course of simple processes in consciousness... give us the most general preliminary conditions, which must be held as a criterion for much more complicated thought-processes.An Introduction to Psychology
The word is the real ideational equivalent for the concept, that cannot be formed into an idea. It changes abstract thoughts into concrete ideational processes that can be heard and seen.An Introduction to Psychology
The thought is as a whole in our consciousness, and at first only works upon the apperception by means of the resulting total feeling, and then develops into its separate component parts by successive acts of apperception. In exactly the same way the artist, the poet, or the composer is accustomed to grasp the whole of the work of art in its outlines, sometimes very indistinct, before he begins to carry out any of the parts.An Introduction to Psychology
Physiological psychology thus ends with those questions with which the philosophical psychology of an older day was wont to begin — the questions of the nature of the mind, and of the relation of consciousness to an external world; and with a characterisation of the general attitude which psychology is to take up, when it seeks to trace the laws of the mental life as manifested in history and in society.Principles of Physiological Psychology Vol I