For Plato, the world of forms stood apart from the world, whereas for Aristotle, the being-what-it-is of an individual is its form. (see transcendence / immanence ) 

For Aristotle, the generation of each organism was the result of a male formal cause (conveyed by the semen) and a female material cause (the menstrual blood.)(see epigenesis

"it is form ... which furnishes the foundation of all biology." (Hans Driesch, 1908, p.17) As used in biology, form is a quality derived from the analysis of an object whereby its underlying structure is represented. Form represents the processes governing the achieved structure of a plant or animal. In modern biology, the concept of organization functions like the Aristotelian concept of form. 

Is there an independent problem of form, for which biology must develop its own concepts and methods of thought? The Pre-Darwinian project of rational morphology was to discover the "laws of form," some inherent necessity in the laws which governed morphological process. It sought to construct what was typical in the varieties of form into a system which should not be merely historically determined, but which should be intelligible from a higher and more rational standpoint. (Hans Driesch, 1914, p. 149) 

Kant's notion of form is intimately tied to the transcendental enterprise, that is, to Kant's attempt to spell out the necessary requirements for human experience in general. Form is a subjective rule for our knowledge of objective reality. It is "that which allows the manifold of appearance to be ordered in certain relations." (Critique of Pure Reason, section 1, 56) The concept of form (along with its correlate, matter) is a concept of reflection. (Reflexionsbegriff ) 

Kant employed the notion of form to define the "pure forms of intuition," (the a priori ideas of space and time) and the "forms of thought" (the categories by which we mediate the manifold of intuitions.) According to Ernst Cassirer, "Kant's basic conviction and presupposition consist rather of this, that there is a universal and essential form of knowledge, and that philosophy is called upon and qualified to discover this form and establish it with certainty." (Cassirer, The Problem of Knowledge, p. 14) This is the task which Cassirer takes up in The Philosophy of Symbolic Forms, which seeks to define both the specific features of the different forms of cultural thought as well as their unifying features. 

Goethe saw form as belonging not only to space but to time as well. In Goethe's own dynamic sense of life, the attributes of the"born poet" and those of the empirical researcher combined in a special feeling for nature and for life. "What does all our communion with nature amount to, indeed," he said, referring to the difference between Cuvier and Geoffroy Saint-Hilaire, "if we busy ourselves with analyzing only single material portions, and do not feel the breath of the spirit that dictates the role of every part and restrains or sanctions all excess through an immanent law?" (quoted in Ernst Cassirer, The Problem of Knowledge, p. 141) Goethe subscribed to neither induction nor deduction, but sought the "pregnant instance," not countless, scattered observations, but that which exhibits the "immanent law" of nature. (cf the importance of prägnanz for gestalt psychology) 

For Henri Focillon, in The Life of Forms in Art, form is "at the very instant of its birth, a phenomenon of rupture" in which multiple temporalities meet and collide, and in the midst of which those ruptures occur that are called events. Like André Leroi-Gourhan, Focillon links form to gesture, to the rhythms of the body. He describes a constant process of metamorphosis, by which the "life of forms is renewed over and over again. Instead of evolving according to fixed postulates, constantly and universally intelligible, it creates various new geometries even at the heart of geometry itself." (p.94) (see perspective

Focillon rejects the philosophical dualism of form / matter. For him a form is not only, as it were, incarnate, but it is invariably incarnation itself. (p101) Form is always, not the desire for action, but action itself." (119-120) 

(see also diagram / abstract machine

Konrad Fiedler defines intellectual work as "a progression from the unformed to the formed." (Empathy, Form, and Space, p.130) In the artistic creation of architecture, material and construction progressively disappear while the form, which is a thing of the mind, develops an increasingly autonomous existence. 

Adolf Hildebrand defined the "Problem of Form in the Fine Arts" (1893) as a particular relation between form and appearance. He contrasted the abstract and unchanging "inherent form" (Daseinsform ) which we attribute to objects, from the changing impressions of "effective form." (Wirkungsform ) (see also perceptual / conceptual ) In everyday life, according to Hildebrand, we engage in various activities that combine seeing and scanning. (see vision) Since we need only to extract a few clues in order to orient ourselves in space, we are not aware of how much our idea of form and space derives from the stimulus of the specific thing seen and how much we ourselves add to it. (see p. 228) The situation is fundamentally different in art. For Hildebrand, "the visual arts alone reflect the active operation of consciousness: the activity that seeks to bridge the gap between ideas of form and visual impressions and to fashion both into a unity." ( Empathy, Form, and Space, p.231) "The true enjoyment of a work of art and its spontaneous blessing lies in the perception of this unity."