_Casuistic_ has had the same fate as the rules, and was also at one time responsible for a very copious literary production. Now it is cultivated as literature only by a few Jesuits, who carry on the glories of Escobar and of Sanchez, read only by priests preparing themselves for the post of confessor, whose studies are based for the most part upon old books (such as the _Theologia moralis_ of the Neapolitan Sant' Alfonso de' Liguori). At one time Casuistic was not confined only to profane or theological morality, to the _casus conscientiae. _ There were also books of casuistry composed for all aspects of life, for politics, for the life of the courtier ("the Wise Man at Court"), for the art of love. When the literary form of rules fell into discredit, that of Casuistic fell with it. But this does not mean that it is dead; it lives and will live as long as rules live. For Casuistic is nothing but the process of reasoning by which rules are made always more precise, passing from more general cases to those more particular, so that no one will ever be able to do without them.--If we take for rule of life this maxim: to avoid scientific polemics, because they constitute a waste of time, adding little to the progress of knowledge; in what way must we behave if a polemic be such that it enables us to gain on the one hand the time it makes us lose on the other? Shall we maintain the general rule, or shall we waive it on this occasion, if for no other reason than to give variety to our occupations? And how shall we behave if not only we retrieve the time lost but avoid losing more time in the future? Shall we wish to enter upon the polemic at once? But if our future be looked upon as uncertain, if we be far advanced in years or in bad health, will it not be better to renounce the uncertain gain of the future for the certain gain of the present?--This is a very simple example of Casuistic, which a critic and writer (let us suppose that he is the writer of these pages) is obliged to propose to himself and to solve. Naturally, no Casuistic will ever furnish the concrete solution (which is the only one that counts), since, as has been said, no rule can ever furnish it. Rules and casuistry do not reach the individuality _omnimodo determinata,_ which is the historical situation; yet if Casuistic aid my action, this will always differ from that, as concrete from abstract; or better, my action will always truly possess the form, the definiteness that abstract casuistry cannot possess. Woe to practical men who rely upon collections of maxims and casuistical reasonings, and woe to those who rely upon them. Those who argue at length upon practical matters and draw subtle distinctions, are to be avoided in the world of affairs and in the world of action. If they have not yet provoked some disaster, they are on the road to doing so now. This, at least, is a good rule; like the supreme rule (which is not a rule but