224 FROM FISH TO PHILOSOPHER 



Five hundred million years of vertebrate evolution have 

 been required to produce this brain, composed of a 

 dozen-odd sorts of atoms; and, given an adequate in- 

 ternal environment, it can know itself in self-awareness 

 for at most some three- or four-score years. 



How all this comes about in the transient interplay of 

 atoms and molecules, no one can answer, but this does 

 not mean that the answer is unattainable. Science ad- 

 vances so rapidly that it would be rash to place a limit 

 on its possibilities, hi essence, the scientific method con- 

 sists of careful observation of nature and cautious con- 

 firmation of all conclusions, to the exclusion of unsub- 

 stantiated hypotheses. A scientist is one who, when he 

 does not know the answer, is rigorously disciplined to 

 speak up and say so unashamedly; which is the essential 

 feature by which modem science is distinguished from 

 primitive superstition, which knew aU the answers ex- 

 cept how to say, 1 do not know.' On every scientist's 

 desk there is a drawer labeled Unknown in which he 

 files what are at the moment unsolved questions, lest 

 through guesswork or impatient speculation he come 

 upon incorrect answers that will do him more harm than 

 good. Man's worst fault is opening the drawer too soon. 

 His task is not to discover final answers but to win the 

 best partial answers that he can, from which others may 

 move confidently against the imknown, to win better 

 ones. 



The atomistic basis of consciousness remains un- 

 known. But by all the evidences it must be sought at 

 the cellular rather than the molecular level. 



There are those who say that the human kidney was 

 created to keep the blood pure, or more precisely, to 

 keep our internal environment in an ideal balanced state. 

 This I must deny. I grant that the human kidney is a 

 marvelous organ, but I cannot grant that it was purpose- 

 fully designed to excrete urine or to regulate the com- 

 position of the blood or to subserve the physiological 



