| the middle term, it must have been | known before. In other words, | syllogistic form leaves the invention | of the middle term to the natural | shrewdness of the mind or to good | fortune. Thus, it is because of its | own demonstrative form that the | syllogism is unable to provide a | method of truth and is useless for | science. | | By now it is clear why the old logic | and the knowledge which is built on it | are unable to produce works or why the | extant works "are due to chance and | experience rather than to sciences" | (IV, 48). To deduce practical effects, | the mind must know real causes or laws | of nature. Since the old method does | not supply the mind with the means of | inventing causes and does not set up | the scale of the intermediate | propositions that are needed to reduce | sensible experience and reach the real | science, or to derive rightly and by | degrees the consequences from the | principles, it is not surprising that | invented works are too few and not | very useful for men's lives. Thus, | from the start in sensible experience | to the end in practical deduction, | this old method is of no use. And an | entirely new one must be proposed, | which will be able to carry the human | mind from empirical data to the real | causes, to supply it with the means of | invention, to justify the position of