3. The third factor is suggestion. The situation in which the perplexity occurs calls up something not present to the senses: the present location, the thought of subway or elevated train; the stick before the eyes, the idea of a flagpole, an ornament, an apparatus for wireless telegraphy; the soap bubbles, the law of expansion of bodies through heat and of their contraction through cold. (_a_) Suggestion is the very heart of inference; it involves going from what is present to something absent. Hence, it is more or less speculative, adventurous. Since inference goes beyond what is actually present, it involves a leap, a jump, the propriety of which cannot be absolutely warranted in advance, no matter what precautions be taken. Its control is indirect, on the one hand, involving the formation of habits of mind which are at once enterprising and cautious; and on the other hand, involving the selection and arrangement of the particular facts upon perception of which suggestion issues. (_b_) The suggested conclusion so far as it is not accepted but only tentatively entertained constitutes an idea. Synonyms for this are _supposition_, _conjecture_, _guess_, _hypothesis_, and (in elaborate cases) _theory_. Since suspended belief, or the postponement of a final conclusion pending further evidence, depends partly upon the presence of rival conjectures as to the best course to pursue or the probable explanation to favor, _cultivation of a variety of alternative suggestions_ is an important factor in good thinking. [Sidenote: 4. The rational elaboration of an idea] 4. The process of developing the bearings--or, as they are more technically termed, the _implications_--of any idea with respect to any problem, is termed _reasoning_.[14] As an idea is inferred from given facts, so reasoning sets out from an idea. The _idea_ of elevated road is developed into the idea of difficulty of locating station, length of time occupied on the journey, distance of station at the other end from place to be reached. In the second case, the implication of a flagpole is seen to be a vertical position; of a wireless apparatus, location on a high part of the ship and, moreover, absence from every casual tugboat; while the idea of index to direction in which the boat moves, when developed, is found to cover all the details of the case. [14] This term is sometimes extended to denote the entire reflective process--just as _inference_ (which in the sense of _test_ is best reserved for the third step) is sometimes used in the same broad sense. But _reasoning_ (or _ratiocination_) seems to be peculiarly adapted to express what the older writers called the "notional" or "dialectic" process of developing the meaning of a given idea.