THE INSTAURATIO MAGNA. This was the most ambitious, though it is not the best known, of Bacon's works. For the insight it gives us into the author's mind, we note here a brief outline of his subject. It was divided into six parts, as follows: 1. _Partitiones Scientiarum_. This was to be a classification and summary of all human knowledge. Philosophy and all speculation must be cast out and the natural sciences established as the basis of all education. The only part completed was _The Advancement of Learning_, which served as an introduction. 2. _Novum Organum_, or the "new instrument," that is, the use of reason and experiment instead of the old Aristotelian logic. To find truth one must do two things: (_a_) get rid of all prejudices or idols, as Bacon called them. These "idols" are four: "idols of the tribe," that is, prejudices due to common methods of thought among all races; "idols of the cave or den," that is, personal peculiarities and prejudices; "idols of the market place," due to errors of language; and "idols of the theater," which are the unreliable traditions of men. (_b_) After discarding the above "idols" we must interrogate nature; must collect facts by means of numerous experiments, arrange them in order, and then determine the law that underlies them. It will be seen at a glance that the above is the most important of Bacon's works. The _Organum_ was to be in several books, only two of which he completed, and these he wrote and rewrote twelve times until they satisfied him. 3. _Historic Naturalis et Experimentalis_, the study of all the phenomena of nature. Of four parts of this work which he completed, one of them at least, the _Sylva Sylvarum_, is decidedly at variance with his own idea of fact and experiment. It abounds in fanciful explanations, more worthy of the poetic than of the scientific mind. Nature is seen to be full of desires and instincts; the air "thirsts" for light and fragrance; bodies rise or sink because they have an "appetite" for height or depth; the qualities of bodies are the result of an "essence," so that when we discover the essences of gold and silver and diamonds it will be a simple matter to create as much of them as we may need. 4. _Scala Intellectus_, or "Ladder of the Mind," is the rational application of the _Organum_ to all problems. By it the mind should ascend step by step from particular facts and instances to general laws and abstract principles. 5. _Prodromi_, "Prophecies or Anticipations," is a list of discoveries that men shall make when they have applied Bacon's methods of study and experimentation. 6. _Philosophia Secunda_, which was to be a record of practical results of the new philosophy when the succeeding ages should have applied it faithfully.