This detailed and accurate description of exactly what takes place shows us Adelard’s powers of observation and experiment at their best, and compares favorably with two cruder examples of experimentation which he ascribes to others. He states that it was discovered experimentally which portion of the brain is devoted to the imagination and which parts to reason and memory through a case in which a man was injured in the front part of the head.[88] In the other instance some philosophers, in order to study the veins and muscles of the human body, bound a corpse in running water until all the flesh had been removed by the current.[89] But the question remains, how often did Abelard exercise his powers of accurate observation by actual experiments? Certainly one thing is noteworthy, that the best and almost sole experiment that he details is represented by him as suggested by the magic water jar of an enchantress. Thus we are once again impelled to the conclusion that experimental method owes a considerable debt to magic, and that magic owed a great deal to experimental method. [Sidenote: Adelard and Hero of Alexandria.] We are also reminded of the association of similar water-jars with thaumaturgy in the _Pneumatics_ of Hero of Alexandria.[90] It will be noted that Adelard is content with a single illustration of the principle involved, while Hero kept reintroducing instances of it. And while Hero gave little more than practical directions, Adelard gives a philosophical interpretation of and scientific deduction from the experiment. But he also describes what actually occurs more accurately, admitting that some liquid will gradually flow out even when the air-hole is kept closed. Here again, as in the case of the theory of the penetration of the particles of one substance between those of another mentioned in our paragraph above on the theory of sound, it is difficult to say whether Adelard was acquainted with Hero’s works. Probably it is only chance that Hero’s _Pneumatics_ seems to contain almost exactly the same number of theorems as Adelard’s _Natural Questions_ has chapters.[91] [Sidenote: Attitude to the stars: _De eodem et diverso_.]