_The error of the confusion of cause and effect.—_There is no more dangerous error than to confound the effect with the cause: I call this error the intrinsic perversion of reason. Nevertheless this error is one of the most ancient and most recent habits of mankind. In one part of the world it has even been canonised; and it bears the name of “Religion” and “Morality.” Every postulate formulated by religion and morality contains it. Priests and the promulgators of moral laws are the promoters of this perversion of reason.—Let me give you an example. Everybody knows the book of the famous Cornaro, in which he recommends his slender diet as the recipe for a long, happy and also virtuous life. Few books have been so widely read, and to this day many thousand copies of it are still printed annually in England. I do not doubt that there is scarcely a single book (the Bible of course excepted) that has worked more mischief, shortened more lives, than this well-meant curiosity. The reason of this is the confusion of effect and cause. This worthy Italian saw the cause of his long life in his diet: whereas the prerequisites of long life, which are exceptional slowness of molecular change, and a low rate of expenditure in energy, were the cause of his meagre diet He was not at liberty to eat a small or a great amount. His frugality was not the result of free choice, he would have been ill had he eaten more. He who does not happen to be a carp, however, is not only wise to eat well, but is also compelled to do so. A scholar of the present day, with his rapid consumption of nervous energy, would soon go to the dogs on Cornaro’s diet. _Crede experto._— 2