[26] Cf. Ch. 16 of Supplement.
[27] Cf. Ch. xviii. of the Supplement.
[28] We can thus by no means agree with Bacon if he (De Augm. Scient., L. iv. in fine.) thinks that all mechanical and physical movement of bodies has always been preceded by perception in these bodies; though a glimmering of truth lies at the bottom of this false proposition. This is also the case with Kepler's opinion, expressed in his essay De Planeta Martis, that the planets must have knowledge in order to keep their elliptical courses so correctly, and to regulate the velocity of their motion so that the triangle of the plane of their course always remains proportional to the time in which they pass through its base.