... The Actual And Physical Conduct Of

We Have Usually No Knowledge That Any One Factor Will Exert Its Effects Independently Of All Others That Can Be Varied, Or That Its Effects Are Particularly Simply Related To Variations In These Other Factors.

... No Scientific Worker Has A Fixed Level Of Significance At Which From Year To Year, And In All Circumstances, He Rejects Hypotheses; He Rather Gives His Mind To Each Particular Case In The Light Of His Evidence And His Ideas.

A Book That I Rate Only Second In Importance In Evolution Theory To Darwin 's Origin (this As Joined With Its Supplement Of Man), And Also Rate As Undoubtedly One Of The Greatest Books Of The Twentieth Century

Natural Selection Is A Mechanism For Generating An Exceedingly High Degree Of Improbability.

The Neutral Zone Of Selective Advantage In The Neighbourhood Of Zero Is Thus So Narrow That Changes In The Environment, And In The Genetic Constitution Of Species, Must Cause This Zone To Be Crossed And Perhaps Recrossed Relatively Rapidly In The Course Of Evolutionary Change, So That Many Possible Gene Substitutions May Have A Fluctuating History Of Advance And Regression Before The Final Balance Of Selective Advantage Is Determined.