In fact, in our experiment the attention of the little child was not artificially maintained by a teacher; it was an object which fixed that attention, as if it corresponded to some internal impulse; an impulse which evidently was directed solely to the things "necessary" for its development. In the same manner, those complex coordinated movements achieved by a new-born infant in the act of sucking, are limited to the first and unconscious need of nutrition; they are not a conscious acquisition directed to a purpose. Indeed, the conscious acquisition directed to a definite purpose would be impossible in the movements of a new-born infant's mouth, as also in the first movements of the child's spirit. Therefore it is essential that the external stimulus which first presents itself should be verily the breast and the milk of the spirit, and then only shall we behold that surprising phenomenon of a little face concentrated in an intensity of attention. Behold a child of three years old capable of repeating the same exercise fifty times in succession; many persons are moving about beside him; some one is playing the piano; children are singing in chorus; but nothing distracts the little child from his profound concentration. Just so does the suckling keep hold of the mother's breast, uninterrupted by external incidents, and desists only when he is satisfied. Only Nature accomplishes such miracles. If, then, psychical manifestations have their root in Nature, it was necessary, in order to understand and help Nature, to study it in its initial periods, those which are the simplest, and the only ones capable of revealing truths which would serve as guides for the interpretation of later and more complex manifestations. This, indeed, many psychologists have done; but, applying the analytical methods of experimental psychology, they did not start from that point whence the biological sciences derive their knowledge of life: that is, the _liberty_ of the living creatures they desire to observe. If Fabre had not made use of insects, while leaving them free to carry out their natural manifestations, and observing them without allowing his presence to interfere in any way with their functions; if he had caught insects, had taken them into his study, and subjected them to experiment, he would not have been able to reveal the marvels of insect life. If bacteriologists had not instituted, as a method of research, an environment similar to that which is natural to microbes, both as regards nutritive substances and conditions of temperature, etc., to the end that they "might live freely" and thus manifest their characteristics; if they had confined themselves to fixing the germs of a disease under the microscope, the science which to-day saves the lives of innumerable men and protects whole nations from epidemics would not exist. Freedom to live is the true basis for every method of observation applied to living creatures.