X. The object of our philosophy being thus laid down, we proceed to precepts, in the most clear and regular order. The signs for the interpretation of nature comprehend two divisions; the first regards the eliciting or creating of axioms from experiment, the second the deducing or deriving of new experiments from axioms. The first admits of three subdivisions into ministrations. 1. To the senses. 2. To the memory. 3. To the mind or reason. For we must first prepare as a foundation for the whole, a complete and accurate natural and experimental history. We must not imagine or invent, but discover the acts and properties of nature. But natural and experimental history is so varied and diffuse, that it confounds and distracts the understanding unless it be fixed and exhibited in due order. We must, therefore, form tables and co-ordinations of instances, upon such a plan, and in such order that the understanding may be enabled to act upon them. Even when this is done, the understanding, left to itself and to its own operation, is incompetent and unfit to construct its axioms without direction and support. Our third ministration, therefore, must be true and legitimate induction, the very key of interpretation. We must begin, however, at the end, and go back again to the others. XI. The investigation of forms proceeds thus: a nature being given, we must first present to the understanding all the known instances which agree in the same nature, although the subject matter be considerably diversified. And this collection must be made as a mere history, and without any premature reflection, or too great degree of refinement. For instance; take the investigation of the form of heat. _Instances agreeing in the Form of Heat_ 1. The rays of the sun, particularly in summer, and at noon. 2. The same reflected and condensed, as between mountains, or along walls, and particularly in burning mirrors. 3. Ignited meteors. 4. Burning lightning. 5. Eruptions of flames from the cavities of mountains, etc. 6. Flame of every kind. 7. Ignited solids. 8. Natural warm baths. 9. Warm or heated liquids. 10. Warm vapors and smoke; and the air itself, which admits a most powerful and violent heat if confined, as in reverberating furnaces. 11. Damp hot weather, arising from the constitution of the air, without any reference to the time of the year. 12. Confined and subterraneous air in some caverns, particularly in winter. 13. All shaggy substances, as wool, the skins of animals, and the plumage of birds, contain some heat. 14. All bodies, both solid and liquid, dense and rare (as the air itself), placed near fire for any time. 15. Sparks arising from the violent percussion of flint and steel. 16. All bodies rubbed violently, as stone, wood, cloth, etc., so that rudders, and axles of wheels, sometimes catch fire, and the West Indians obtain fire by attrition.