欧拉致德国公主的书信：关于自然哲学的不同学科（第 II 卷 英文版）

LETTER I． Continuation of the Subject， and of Mistakes in the Knowledge of Truth

LETTER II． First Class of Known Truths． Conviction That Things Exist Externally， Corresponding to the Ideas Represented by the Senses， Objection of the Pyrrhonists Reply

LETTER III． Another Objection of the Pyrrhonists against the Certainty of Truths Perceived by the Senses． Reply； and Precautions for Attaining Assurance of Sensible Truths

LETTER IV． Of Demonstrative， Physical， and Particularly of Moral Certainty

LETTER V． Remarks that the Senses Contribute to the Increase of Knowledge； and Precautions for Acquiring the Certainty of Historical Truths

LETTER VI． Whether the Essence of Bodies be Known by Us

LETTER VII． The True Notion of Extension

LETTER VIII． Divisibility of Extension in Infinitum

LETTER IX． Whether This Divisibility in Infinitum Takes Place in Existing Bodies

LETTER X． Of Monads

LETTER XI． Refiections on Divisibility in Infinitum， and on Monads

LETTER XII． Reply to the Objections of the Monadists to Divisibility in Infinitum

LETTER XIII． Principle of the Sufficient Reason， the Strongest Support of the Monadists

LETTER XIV． Another Argument of the Monadists， Derived from the Principle of the Sufficient Reason． Absurdities Resulting from It

LETTER XV． Reflections on the System of Monads

LETTER XVI． Continuation

LETTER XVII． Conclusion of Reflections on This System

LETTER XVIII． Elucidation Respecting the Nature of Colours

LETTER XIX． Reflections on the Analogy between Colours and Sounds

LETTER XX． Continuation

LETTER XXI． How Opaque Bodies are Rendered Visible

LETTER XXII． The Wonders of the Human Voice

LETTER XXIII． A Summary of the Principal Phenomena of Electricity

LETTER XXIV． The True Principle of Nature on Which Are Founded All the Phenomeria of Electricity

LETTER XXV． Continuation． Different Nature of Bodies Relatively to Electricity

LETTER XXVI． On the Same Subject

LETTER XXVII． Of Positive and Negative Electricity．Explanation of the Phenomenon of Attraction

LETTER XXVIII． On the Same Subject

LETTER XXIX． On the Electric Atmosphere

LETTER XXX． Communication of Electricity to a Bar of iron， by Means of a Globe of Glass

LETTER XXXL Electrization of Men and Animals