Man's primary natural goals are, therefore, to measure himself against his environment, to discover in every object he sees those sensible qualities which may concern himself, so his first study is a kind of experimental physics for his own preservation. He is turned away from this and sent to speculative studies before he has found his proper place in the world. While his delicate and flexible limbs can adjust themselves to the bodies upon which they are intended to act, while his senses are keen and as yet free from illusions, then is the time to exercise both limbs and senses in their proper business. It is the time to learn to perceive the physical relations between ourselves and things. Since everything that comes into the human mind enters through the gates of sense, man's first reason is a reason of sense-experience. It is this that serves as a foundation for the reason of the intelligence; our first teachers in natural philosophy are our feet, hands, and eyes. To substitute books for them does not teach us to reason, it teaches us to use the reason of others rather than our own; it teaches us to believe much and know little. Before you can practise an art you must first get your tools; and if you are to make good use of those tools, they must be fashioned sufficiently strong to stand use. To learn to think we must therefore exercise our limbs, our senses, and our bodily organs, which are the tools of the intellect; and to get the best use out of these tools, the body which supplies us with them must be strong and healthy. Not only is it quite a mistake that true reason is developed apart from the body, but it is a good bodily constitution which makes the workings of the mind easy and correct. While I am showing how the child's long period of leisure should be spent, I am entering into details which may seem absurd. You will say, "This is a strange sort of education, and it is subject to your own criticism, for it only teaches what no one needs to learn. Why spend your time in teaching what will come of itself without care or trouble? Is there any child of twelve who is ignorant of all you wish to teach your pupil, while he also knows what his master has taught him." Gentlemen, you are mistaken. I am teaching my pupil an art, the acquirement of which demands much time and trouble, an art which your scholars certainly do not possess; it is the art of being ignorant; for the knowledge of any one who only thinks he knows, what he really does know is a very small matter. You teach science; well and good; I am busy fashioning the necessary tools for its acquisition. Once upon a time, they say the Venetians were displaying the treasures of the Cathedral of Saint Mark to the Spanish ambassador; the only comment he made was, "Qui non c'e la radice." When I see a tutor showing off his pupil's learning, I am always tempted to say the same to him.