Further, it is held that all science can be taught, and that what can be known in the way of science can be learnt. But all teaching starts from something already known, as we have explained in the Analytics; for it proceeds either by induction or by syllogism. Now, it is induction that leads the learner up to universal principles, while syllogism starts from these. There are principles, then, from which syllogism starts, which are not arrived at by syllogism, and which, therefore, must be arrived at by induction. 143

Science, then, may be defined as a habit or formed faculty of demonstration, with all the further qualifications which are enumerated in the Analytics. It is necessary to add this, because it is only when the principles of our knowledge are accepted and known to us in a particular way, that we can properly be said to have scientific knowledge; for unless these principles are better known to us than the conclusions based upon them, our knowledge will be merely accidental. 144

This, then, may be taken as our account of science.