You have chosen 'On Duties ('De Officiis')' by M. Tullius Cicero, 'Nature and Utility of Religion' by John Stuart Mill and 'Popular Scientific Lectures' by Ernst Mach
start again | choose another area for these texts | all the ideas for this combination of texts| All the ideas for Natural Theory, or select a subheading: |
| A. | Speculations on Nature | |
| B. | Natural Kinds | |
| C. | Causation | |
| D. | Laws of Nature |