“Educazione e criminalità” is the title of the third chapter. The human brain is an organic mechanism, similar (but with numerous exceptions) to an inorganic mechanism in this, that it is subject to the great law of the conservation of energy, which manifests itself, among other ways, in inertia. From which it comes that man at all times has had an irresistible tendency to make use of a general principle as a basis for his logical structures. Without this he would always be forced to build each new structure from the ground up, which would involve the waste of too much cerebral energy. Opposed to this law is another which teaches us that life is impossible in a state of absolute repose, but that it requires a perpetual changing of the organic and physio-psychic materials. Hence it comes that eternal and absolute truths change at different epochs, and that they seem stable only when compared with the secondary truths, which are subject to the fashions of the time. According to the author, then, there are truths that are more general and nearly inalterable, but there are others which, though general also, are more secondary, only retain their force during several generations, and end by being changed. Such, for example, are the views concerning human life, formulated by the great thinkers, then accepted by the majority, and finally supplanted by other truths. This is why science makes progress by dogmas. It is modern science that has made the great step in recognizing that these dogmas are relative and alterable. Against this reasoning two objections can be alleged. First, that Spencer has given the name “hypothesis” to his doctrine of evolution, while Professor Ferri calls it a dogma. The author on the other hand thinks that his opinions and those of Spencer are exactly alike, for he calls the doctrine in question a relative and alterable dogma, and Spencer says of it: what I have given is an hypothesis; but so long as there is nothing better, that will explain a greater number of facts, I have a right to consider it as the image of the knowable truth, until the contrary is proved. In the second place, it may be asked: “Does man always oscillate between truth and error; will he never know an absolute and eternal truth?” According to Professor Ferri the answer to this question is not difficult. The origin as well as the aim of faith is the effort to give to men a relatively stable support, which they cannot find elsewhere. All discussion with the adherents of a theological opinion is excluded; and as for the others, ought they not to recognize that the life of human thought is just the constant proof of the continual modification of the so-called eternal verities?