Adolf Remane was primarily a morphologist and systematist. In 1952, he published an influential book on the foundations of systematics and phylogenetics in which he advocated homology as the central concept of morphology and the basis of the natural system and discussed criteria serving to discriminate homology from homoplasy in great detail. During the decades when the Modern Synthesis of evolution was created, he repeatedly commented on and criticised the synthetic theory of evolution, which he never fully accepted. Remane disapproved of idealistic morphology and was strongly opposed to Lamarckian, saltationist and orthogenetic theories of evolution. Yet, while appreciating the synthetic theory's validity in the realm of speciation and microevolution, he rejected the claim that the current genetic knowledge was sufficient to explain complex morphological transformations on the basis of random mutations and selection. Instead, he seems to have favoured mutation pressure as the most important factor in macroevolution. Nevertheless, the sometimes vicious disputes between Remane and the adherents of the Modern Synthesis may at least partly have been brought about by personal factors rather than by scientific differences.