But what the intellect knows clearly is only the word itself and its steering function.  So it comes about that intellects SIBI PERMISSI, intellects only curious and idle, have forsaken the common-sense level for what in general terms may be called the ‘critical’ level of thought.  Not merely such intellects either—­your Humes and Berkeleys and Hegels; but practical observers of facts, your Galileos, Daltons, Faradays, have found it impossible to treat the NAIFS sense-termini of common sense as ultimately real.  As common sense interpolates her constant ‘things’ between our intermittent sensations, so science EXTRApolates her world of ‘primary’ qualities, her atoms, her ether, her magnetic fields, and the like, beyond the common-sense world.  The ‘things’ are now invisible impalpable things; and the old visible common-sense things are supposed to result from the mixture of these invisibles.  Or else the whole NAIF conception of thing gets superseded, and a thing’s name is interpreted as denoting only the law or Regel der VERBINDUNG by which certain of our sensations habitually succeed or coexist.

Science and critical philosophy thus burst the bounds of common sense.  With science NAIF realism ceases:  ‘Secondary’ qualities become unreal; primary ones alone remain.  With critical philosophy, havoc is made of everything.  The common-sense categories one and all cease to represent anything in the way of being; they are but sublime tricks of human thought, our ways of escaping bewilderment in the midst of sensation’s irremediable flow.

But the scientific tendency in critical thought, tho inspired at first by purely intellectual motives, has opened an entirely unexpected range of practical utilities to our astonished view.  Galileo gave us accurate clocks and accurate artillery-practice; the chemists flood us with new medicines and dye-stuffs; Ampere and Faraday have endowed us with the New York subway and with Marconi telegrams.  The hypothetical things that such men have invented, defined as they have defined them, are showing an extraordinary fertility in consequences verifiable by sense.  Our logic can deduce from them a consequence due under certain conditions, we can then bring about the conditions, and presto, the consequence is there before our eyes.  The scope of the practical control of nature newly put into our hand by scientific ways of thinking vastly exceeds the scope of the old control grounded on common sense.  Its rate of increase accelerates so that no one can trace the limit; one may even fear that the being of man may be crushed by his own powers, that his fixed nature as an organism may not prove adequate to stand the strain of the ever increasingly tremendous functions, almost divine creative functions, which his intellect will more and more enable him to wield.  He may drown in his wealth like a child in a bath-tub, who has turned on the water and who cannot turn it off.