  It is no doubt clear at this point that a large part of the question how we gain natural knowledge has not yet been treated, for we have not yet discussed how it is one acquires knowledge of the first principles that enter into demonstration. Grosseteste allowed two forms of knowledge. In first principles per se in the first way (so that the predicate is contained in the subject) he suggested that through sensory experience of particulars of a natural kind, one's intellect is aroused, and comes to a vision of the real nature of the thing which is expressed in the real definition of the subject. (Aquinas has a similar view concerning the first principles of a demonstration of the highest sort. With acquaintance with the real definition of a substantial nature, one can simply see, intellectually, what its immediate powers are.) Since the predicate is contained in the subject, once we have a real definition of the subject in hand, we simply see that the first principle is true. Roughly speaking, we will simply see what functions a natural thing has once we understand what it is formally, though we will not yet see how it manages to execute those functions.