he is credited with first mentioning in this work of staining of bone, with madder root. in the same work he gives credence to the theory of maternal impression; his theory of teratology connects the aristotelian theory of generation with birth defects. he contributed to demonology, with johann weyer, by suggesting that mental illness and disturbance could be physically caused, rather than being a result of outside influence. he also credited solomon with the invention of the magnetic compass.