CHAPTER II.
OUR KNOWLEDGE OF EXTERNAL OBJECTS IS ONLY SENSATIONS Of late years numerous studies have been published on the conception of matter, especially by physicists, chemists, and mathematicians.
Among these recent contributions to science I will quote the articles of Duhem on the Evolution of Mechanics published in 1903 in the _Revue generale des Sciences_, and other articles by the same author, in 1904, in the _Revue de Philosophie_.

Duhem's views have attracted much attention, and have dealt a serious blow at the whole theory of the mechanics of matter.

Let me also quote that excellent work of Dastre, _La Vie et la Mort_, wherein the author makes so interesting an application to biology of the new theories on energetics; the discussion between Ostwald and Brillouin on matter, in which two rival conceptions find themselves engaged in a veritable hand-to-hand struggle (_Revue generale des Sciences_, Nov.

and Dec.

1895); the curious work of Dantec on _les Lois Naturelles_, in which the author ingeniously points out the different sensorial districts into which science is divided, although, through a defect in logic, he accepts mechanics as the final explanation of things.