The Gestalt concept of isomorphism has been subject to many misinterpretations, which at least in part must be credited to some obscurities in classic Gestaltist writings. One refers to the very name “isomorphism”: why Köhler chose it? Another ambiguity refers to the domains supposed isomorphic: external word, phenomenal world and physiological world. A third ambiguity contrasts the direct experience to the representations. The fourth contrasts structural versus functional isomorphism. The fifth is ontological: why some authors can interpret isomorphism as a dualistic concept? I try to solve all this ambiguities going back to Spinoza, possibly a primary source of inspiration, at least for Wertheimer.
