The twofold grade of the theoretical activity, aesthetic and logical, has an important parallel in the practical activity, which has not yet been placed in due relief. The practical activity is also divided into a first and second degree, the second implying the first. The first practical degree is the simply _useful_ or _economical_ activity; the second the _moral_ activity. Economy is, as it were, the Aesthetic of practical life; Morality its Logic. [Sidenote] _The economically useful._ If this has not been clearly seen by philosophers; if its suitable place in the system of the mind has not been given to the economic activity, and it has been left to wander in the prolegomena to treatises on political economy, often uncertain and but slightly elaborated, this is due, among other reasons, to the fact that the useful or economic has been confused, now with the concept of _technique_, now with that of the _egoistic_. [Sidenote] _Distinction between the useful and the technical._ _Technique_ is certainly not a special activity of the spirit. Technique is knowledge; or better, it is knowledge itself, in general, that takes this name, as we have seen, in so far as it serves as basis for practical action. Knowledge which is not followed, or is presumed to be not easily followed by practical action, is called pure: the same knowledge, if effectively followed by action, is called applied; if it is presumed that it can be easily followed by the same action, it is called technical or applied. This word, then, indicates a _situation_ in which knowledge already is, or easily can be found, not a special form of knowledge. So true is this, that it would be altogether impossible to establish whether a given order of knowledge were, intrinsically, pure or applied. All knowledge, however abstract and philosophical one may imagine it to be, can be a guide to practical acts; a theoretical error in the ultimate principles of morals can be reflected and always is reflected in some way, in practical life. One can only speak roughly and unscientifically of truths that are pure and of others that are applied. The same knowledge which is called technical, can also be called _useful_. But the word "useful," in conformity with the criticism of judgments of value made above, is to be understood as used here in a linguistic or metaphorical sense. When we say that water is useful for putting out fire, the word "useful" is used in a non-scientific sense. Water thrown on the fire is the cause of its going out: this is the knowledge that serves for basis to the action, let us say, of firemen. There is a link, not of nature, but of simple succession, between the useful action of the person who extinguishes the conflagration, and this knowledge. The technique of the effects of the water is the theoretical activity which precedes; the _action_ of him who extinguishes the fire is alone useful. [Sidenote] _Distinction between the useful and the egoistic._