Theoretical neuromorphology is the science of using morphology to mathematically describe the shape and the connectivity in the nervous system. History The rational study of shapes has been long to form. In the major progresses made during the last century, it is important to differentiate morphogenesis (the way forms are made) and morphology (realized forms). Morphogenesis Important conceptual changes about forms came from d'Arcy Thompson’s essay (1917) dealing with forms in nature. These were not considered as static but as the result of morphogenetic factors. Not knowable in its intimate nature, form is defined as the simple result of forces. Thom (1974), founder of the "catastrophe theory" acknowledged what he owed to this work. A series of various branches of non-linear mathematics catastrophe theory, the fractal theory, the theory of "dissipative structures", the chaos theory have led to what Boutot (1993) called "the morphologic revolution", which has deeply modified the conception of forms in space. Theoretical neuromorphology discards morphogenesis (the way forms have been made) to limit its purpose to realised forms. Neuromorphology In spite of some results, space and shapes were often not considered as susceptible of bringing information on the nervous system functioning. Neuromorphology yet had been intensively studied after the discovery of the Golgi method allowing to see entire neurons. This gave rise to an abundant literature, with descriptions and figures. This allowed Ramon y Cajal (1911) to found definitely the "neuron theory" (the brain is constituted of separate cells that communicate together) and to formulate the law of "dynamic polarization" (axonalwards). With others, he pointed out the variety of patterns of neurons depending on particular cerebral places and already emitted hypotheses on the roles that could be played by particular forms. Several attempts have been made later. One step has been the work of Mannen (1960) on closed and open nuclei reinsisting on dendritic morphology. This was followed by several papers of Ramon-Moliner defining types of neurons according to their dendritic arborisations. Formalisation An approach of natural forms was proposed by Stevens (1974) who tried to rationally make classification of forms and to find their specific properties and advantages in terms of directness or economy of ways. Since almost one century, an important corpus of theoretical tools, still poorly exploited, has revealed to be very helpful for the understanding of the nervous system. These tools, generally, may be classified as «logical » or more narrowly as