[Sidenote: Three important natural resources] Any inventory of the items of this natural capital is somewhat arbitrary because it must pass over many of the complex details. But a statement of the factors essential to thought will put before us in outline the main elements. Thinking involves (as we have seen) the suggestion of a conclusion for acceptance, and also search or inquiry to test the value of the suggestion before finally accepting it. This implies (_a_) a certain fund or store of experiences and facts from which suggestions proceed; (_b_) promptness, flexibility, and fertility of suggestions; and (_c_) orderliness, consecutiveness, appropriateness in what is suggested. Clearly, a person may be hampered in any of these three regards: His thinking may be irrelevant, narrow, or crude because he has not enough actual material upon which to base conclusions; or because concrete facts and raw material, even if extensive and bulky, fail to evoke suggestions easily and richly; or finally, because, even when these two conditions are fulfilled, the ideas suggested are incoherent and fantastic, rather than pertinent and consistent. § 1. _Curiosity_ [Sidenote: Desire for fullness of experience:] The most vital and significant factor in supplying the primary material whence suggestion may issue is, without doubt, curiosity. The wisest of the Greeks used to say that wonder is the mother of all science. An inert mind waits, as it were, for experiences to be imperiously forced upon it. The pregnant saying of Wordsworth: "The eye--it cannot choose but see; We cannot bid the ear be still; Our bodies feel, where'er they be, Against or with our will"-- holds good in the degree in which one is naturally possessed by curiosity. The curious mind is constantly alert and exploring, seeking material for thought, as a vigorous and healthy body is on the _qui vive_ for nutriment. Eagerness for experience, for new and varied contacts, is found where wonder is found. Such curiosity is the only sure guarantee of the acquisition of the primary facts upon which inference must base itself. [Sidenote: (_a_) physical]