"The title represents a late use of the word Physiological in its original Greek sense of signifying all natural knowledge. It contains discourses on Physics, Chemistry, Meteorology and kindred subjects. It also contains the diverting essay on The Unsuccessfulness of Experiments" (Duveen). Fulton stresses that its importance "lies in the fact that in a very real sense it was a 'prologue' to the more widely known Sceptical chymist since it continued the attack on the alchemists begun in New Experiments, and actually it was as much of a landmark in the history of chemistry. In the Essays Boyle gives the first clear outline of his corpuscular hypothesis concerning the nature of matter, which was to be the guiding principle of all his later chemical studies." The book was widely read, appearing twice in English and nine times in Latin.