Beyond the general principle of utility, therefore, we have to consider the 'organon' constructed by him to give effect to a general principle too vague to be applied in detail. The fullest account of this is contained in the _Introduction to the Principles of Morals and Legislation_. This work unfortunately is a fragment, but it gives his doctrine vigorously and decisively, without losing itself in the minute details which become wearisome in his later writings. Bentham intended it as an introduction to a penal code; and his investigation sent him back to more general problems. He found it necessary to settle the relations of the penal code to the whole body of law; and to settle these he had to consider the principles which underlie legislation in general. He had thus, he says, to 'create a new science,' and then to elaborate one department of the science. The 'introduction' would contain prolegomena not only for the penal code but for the other departments of inquiry which he intended to exhaust.[356] He had to lay down primary truths which should be to this science what the axioms are to mathematical sciences.[357] These truths therefore belong to the sphere of conduct in general, and include his ethical theory.