It is very amusing to assist at the acts of repulsion and of exorcism, which a man like the Abbé Galiani believes himself obliged to make in his treatise _Dei doveri dei principi neutrali_ (1782). When, having amply discussed this matter from the point of view of morality, he goes on to discuss it from the point of view of politics and of the reason of State, he despatches it in a few pages, abhorring, as he says, that "insidious and wicked science" which formed "the delight, first of Italian and then of almost all European minds of the fifteenth and seventeenth centuries." He protests at every step that he is "tired of repeating and of developing teachings of cunning and wickedness." But what the Abbot Galiani really abhorred was the robed scholastic treatment of a matter that he who was termed _Machiavellino_ by his French friends, and declared that he did not admit in politics anything but _le machiavélisme pur, sans mélange, cru, vert, dans toute son âpreté,_[3] handled with very different ability and elegance in his conversations in Parisian _salons_ and in his witty letters to Madame d'Épinay. The rules of the eighteenth century are to be sought in the speeches, essays, political opuscules, tragedies, plays dealing with the life of citizens, fiction, history, and books of memoirs. If Aretino and Piccolomini provided for the necessities of the respectable courtesans and procuresses of the Cinquecento, in the Settecento, Giacomo Casanova constructed the type of the perfect adventurer. He began with the rules to be followed as a system of life, the _se laisser aller au gré du vent qui pousse,_ and passed to those that were more special and yet fundamental, such as that one should have no scruples _de tromper des étourdis, des fripons et des sots,_ because they _défient l'esprit_ and _on venge l'esprit quand on trompe un sot._ There should be still less scruple in deception in affairs of love, for, _pour ce qui regarde les femmes, ce sont des tromperies réciproques, qu'on ne met pas en ligne de compte; car, quand l'amour s'en mêle, on est ordinairement dupe de part et d'autre_.[4] Let us leave to the reader to investigate, if he please, the rules of life that are concealed beneath the most modern forms of literature; these are a continuous, if not always beneficent, guide for daily life. [Sidenote: _Relation between the arts (collections of rules) and philosophical doctrines._]