Well, we admit that every lesson infringes the liberty of the child, and for this reason we allow it to last only for a few seconds: just the time to pronounce the two words: hot, cold; but this is effected under the influence of the preparation, which by first isolating the sense makes, as it were, a darkness in the consciousness, and then projects only two images into it. As if from the screen before a magic lantern, the child receives his psychical acquisitions, or rather they are like seeds falling on a fertile soil; and it is in the subsequent free choice, and the repetition of the exercise, as in the subsequent activity, spontaneous, associative, and reproductive, that the child will be left "free." He receives, rather than a lesson, a determinate impression of contact with the external world; it is the clear, scientific, pre-determined character of this contact which distinguishes it from the mass of indeterminate contacts which the child is continually receiving from his surroundings. The multiplicity of such indeterminate contacts will create chaos within the mind of the child; pre-determined contacts will, on the other hand, initiate order therein, because with the help of the technique of isolation, they will begin to make him distinguish one thing from another. The technique of our lessons is governed by experimental psychology. And this trend, without doubt, is in contrast to that of the past, which was governed by speculative psychology, on which the whole of the educational methods commonly in use in schools has hitherto been based. It was Herbart who used the philosophical psychology of his day as a guiding principle to reduce pedagogic rules to a system. From his individual experience he believed he could deduce a universal method of developing the mind, and be made this the psychological basis of methods of teaching. The German pedagogist, whose methods are now, thanks to Credaro, formerly Professor of Pedagogy at the University of Rome, and afterward Minister of Education, adopted for elementary education throughout Italy, gave a unique type of lesson on the four well-known periods (the formal steps): clarity, association, system, method. These may be explained approximately as follows: presentation of an object and its analytical examination (clarity); judgment and comparison with other surrounding objects or with mnemonic images (association); definition of the object deduced from preceding judgments (system); new principles derived from the idea which is thus deepened, and which will lead to practical application of a moral order (method).