This volume is made up of papers written by the author over a period of fifteen years concerning philosophy and science intermingled. The group of philosophical essays are introductory to a developed view of the world. The volume also includes a large number of critical and historical papers. Selected contents: the idealism of Spinoza; recent discussion in materialism; the cosmic and the moral; psychology past and present; the origin of emotional expression; the perception of external reality; feeling, belief and judgment; an optical illusion; types of reaction.