It is easy to accept that scientific reasoning cannot determine the characteristics of subjective experiences in cases like Broad's archangel or Jackson's Mary. The author questions why this seems to be evident and discusses the differences between these cases and ordinary scientific work, where future states of studied systems can be predicted in phenomenal terms. He concludes that important limitations of scientific reasoning are due to the inadequacy of human sensorial apparatus for representing physical reality. Such inadequacies were more evident in Mary's case, but are always present, and entail the existence of the explanatory gap.