Finally, since it is impossible that any form whatever of these errors, whether specifically logical or generically philosophic, should satisfy the mind, which asks for the true and does not lend itself to deception or mockery, each one of these forms tends to convert itself into the other, owing to its arbitrariety and untenability, and all mutually destroy one another. When the attempt is made to preserve both the true form and the insufficient form, or all the insufficient forms, we have gnoseological dualism; but with the decline to complete destruction, we have the error of _scepticism_ and of _agnosticism._ Finally, if, having been by these led back to life and being deprived of every concept that should illuminate it back to life as a mystery, we affirm that truth lies in that theoretic mystery, in living life without thought, we have the error of _mysticism._ Dualism, scepticism (or agnosticism) and mysticism thus extend both to strictly logical problems (that is to say, to the possibility, in general, of knowing reality), and to all other philosophic problems. Hence we can speak of a practical dualism, of an æsthetic or ethical scepticism, and of an æsthetic or ethical mysticism. [Sidenote: _Professionalism and nationality of errors._] Such, stated in a summary manner, is the deduction of philosophic errors, which we shall now proceed to examine in detail. Upon their forms, which represent so many tendencies of the human spirit, is based this other fact, which is constantly striking us, and which may be called the _professionalism_ of errors. Every one is disposed to use in other fields of activity those instruments that are familiar to him in the field which he knows best. The poet by vocation and profession dreams and imagines, even when he should reason; the philosopher reasons even when he should be poetical; the historian seeks authority, even when he should seek the necessity of the human mind; the practical man asks himself of what use a thing is, even when he should ask himself what a thing is; the naturalist constructs classes, even when he should break through them, in order to think real things; the mathematician persists in writing formulae, even when there is nothing to calculate. If the narrowness of the _Esprits mathématiques_ has been denounced, it must not be believed that the other professions have not also got their narrownesses. The philosopher's profession is no exception to this, for he should surpass all one-sided views, but does not always succeed. It is one thing to say and another to do, and if a man forewarned is half saved, he is not therefore altogether saved. That professionalism of error, which we observe in individuals, is also to be observed on a large scale among peoples. Thus we speak of peoples as antiartistic, antiphilosophical, or antimathematical: of speculative Germany, of intellectualist and abstract France, of empiricist England, of Italy as artistic in the centre and the north, and as