XXIV.—DESCARTES 172 1. The Beginning of Philosophy with Doubt 173 2. Cogito ergo sum 173 3. The Nature of Mind deduced from this Principle 173 4. The Universal Rule of all Certainty follows from the same 174 5. The Existence of God 174 6. Results of this Fact in Philosophy 176 7. The Two Substances 177 8. The Anthropology of Descartes 177 9. Results of the Cartesian System 178 XXV.—GEULINCX AND MALEBRANCHE 180 1. Geulincx 180 2. Malebranche 182 3. The Defects of the Philosophy of Descartes 183 XXVI.—SPINOZA 184 1. The One Infinite Substance 185 2. The Two Attributes 186 3. The Modes 188 4. His Practical Philosophy 189 XXVII.—IDEALISM AND REALISM 192 XXVIII.—LOCKE 193 XXIX.—HUME 198 XXX.—CONDILLAC 201 XXXI.—HELVETIUS 203 XXXII.-THE FRENCH CLEARING UP AND MATERIALISM 205 1. The Common Character of the French Philosophers of this Age 205 2. Voltaire 206 3. Diderot 206 4. La Mettrie’s Materialism 207 5. Système de la Nature 208 (1.) The Materiality of Man 208 (2.) The Atheism of this System 209 (3.) Its Denial of Freedom and Immortality 210 (4.) The Practical Consequences of these Principles 210