The word "Gestalt" is usually translated as form, although it might be better understoond as "organized structure," as opposed to "heap", aggregate, or simple summation (what Max Wertheimer called "and-sums.")
Goethe introduced the Gestalt concept to nineteenth-century German thought to refer to the self-actualizing wholeness of organic forms. According to his morphology, all advanced structures of a plant or animal are transformations from a single fundamental organ. He accounted for similarities among the members of a species by formal laws of (self-) organization, ultimately derived from an ideal type he calle a Urbild , and attributed the differences to environmental effects. (see natural form)
In Goethe's Color theory, optics and perception are two poles of a single dynamic unity. As he put it to Eckerman, "You see, there is nothing outside us, that is not at the same time in us, and as the external world has its colors, so does the eye as well." (quoted in Ash, p.86) It was this idea of a lawful order realizing itself in nature, not imposed upon it by an ordering mind, and the search for the lawlike (das Gesetzliche) in the phenomena, that provided a model for the Gestalt psychologists of the 20th century.
In the anaysis of Gestalts, the whole is primary. The parts are understood within the systematic whole. A paradigmatic example of "Gestalt qualities" is a melody, which sounds the same in any key. In 1890, Christian von Ehrenfels attributed these qualities to melodies as "a positive quality of presentation," not something projected upon sense data. Ehrenfels extended these qualities to "Gestalt qualities of a higher order," (such as marriage, service, theft, and war) concepts that retain their identity even though the examples that instantiate them change. For philosophers and psychologists of the 1890's, it was not clear whether these qualities of structure were philosophical or psychological. The Gestalt theorists would attempt to integrate both in an experimental science. Jonathan Crary describes Ehrenfels' assertions within the modern problem of form as the attempt to formulate "laws" that would give to perception a semblance of the same unconditional guarantees that vision had had within the classical regime of visuality. (Suspensions of Perception, p. 156)
Gestalt psychology described perception and brain-events as self-organizing systems that spontaneously take on the "best" or simplest arrangement in given conditions. Max Wertheimer explored what he believed to the the fundamental principles of perceptual organization -- the laws of Gestaltung, notably the law of the Prägnanz of the Gestalt, a general tendency toward simple formation, the tendency of a process to realize the most regular, ordered, stable, and balanced state possible in a given situation. Thus "good" or "strong" Gestalts could be distinguised from "bad" or "weak" Gestalts by the stability of simple formation (The word "Gestalt" is also used in German to designate a historical personage, a character who cuts a figure on the historical stage.) The Gestalt laws of grouping included proximity, similarity, good continuation, and closure.
Gestalt theorists opposed the elementaristic and mechanistic assumptions about sensation and consciousness that were shared explicitly or implicitly by all attempts to present psychology as a natural science in the nineteenth century. (Ash, p.60) They asserted the primacy of perception over sensations in the constitution of consciousness, and advanced a conception of the subject as involved in, rather than separated from the world -- ideas that had an important impact on phenomenology and existentialism. Theirs was a quest for an objective (sachlich ) order that lies not behind, but within the flux of experience.
Wolfgang Köhler distinguished Gestalt theories from " machine theory," that is, technological conceptions of science, life, and mind that equated knowledge of nature with its effective manipulation and control. The gestalt theorists attempted to introduce an aesthetic dimension of inherent order, meaning, and simplicity into the evaluation of scientific theories, and into the fabric of experience and nature itself. (Mitchell G. Ash, Gestalt Psychology in German Culture, 1890-1967, p.1)
For the Gestalt theorists, psychological hypotheses referred not to hypothetical mental or emotional processes underlying or producing phenomena, but to principles of self-organization thought to inhere in the phenomena themselves. Köhler hypothesized a psycho-physical isomorphism of structure, which critics often described as a form of "physcialism" -- an attempt to mimic physics, particularly the advanced physics of the twentieth century, with its emphasis on fields rather than particles. In response to the challenges of Hans Driesch, Köhler extended the Gestalt concept to biology in 1924 by elaborating the concept of self-regulating "open" systems, which he distinguished from those described by analytical mechanics.