While Johann Bernoulli's mathematical researches are well-known and highly appreciated, his researches on mechanics have been less studied. His researches on mechanics have been regarded as an inconsistent aggregation of Cartesian, Newtonian and Leibnizian physics; applying calculus to mehcanics as a Newtonian, advocating "vis viva " as a Lebnizian and adopting vortex theory as a Cartesian. The present paper is aiming at showing insufficiency of traditional researches, which arbitrarily selected examplars from Johann Bernoulli's texts and did not read them as such. The author has argued that Johann Bernoulli used common and consistent framework of "loix de la communication du mouvement " (laws of communication of motion) in his papers of 1724 and 1734. These "loix " embodies both conservation of quantity of motion and that of "vis viva ". In the former paper, he applied the law to collision of two bodies. He extended the explanation to the collisions of multiple bodies and to the motion in a resistent medium. In the latter paper, he introduced the mechanism of "torrent central " (central stream). He applied the same law to it and explained gravitation on the basis of the collisions of subtle matter. These above aspects of his original researches have been overlooked, because his texts were not interpreted properly. The author has also suggested that the "loix de la communication du mouvement " is a crucial concept to understand Johann Bernoulli's mature researches on mechanics consistently.
The Hippocratic treatise De Natura Hominis (On the Nature of Man) has been very influential in the history of western medical thought from antiquity, because it argues the theory of four humors as the essential constituents of human body. There has been a traditional view on the theory among scholars that the author Polybos referred to Empedocles' philosophical doctrine of four elements as a model in the formation of the humoral physiology of his own. However, the theory of four humors, as compared with the doctrine of four elements, turns out to be different on the following points. 1) The four elements are introduced as substantial entities, which always remain self-identical, whereas the four humors change into one another, according to the degree of the four elemental qualities (Hot and Cold, Humid and Dry), which constitute their own nature. 2) In the Empedoclean doctrine, human nature comes into being emergently from the four elements, when they come together, or when they separate out of their primordial lump. In NH, the generation process seems to be dependent on human nature, which exists as the determinant of the conditions under which the generation can take place. 3) The Empedoclean cosmic cycle functions as a structural framework, within which the generation takes place. The cosmic system in NH has its own purpose of giving a causal explanation about how the four humors increase and decrease reciprocally in the human body, according to the alternation of the four seasons. These results will make us suppose that the philosophical influences of Empedocles on the theory of four humors remained within a very limited scope, although there are traces in some phrases and sentences as well as forms of argumentation in NH, which may be judged to be reflection of the Empedoclean philosophical poems.