SECTION 22. OBSERVATION. 307 



(g) approaching the unknown and remote from the side of 

 the known and near (as in geology); 



(h) selection of pure, conveniently large, and simplified in- 

 stances (as in botany and physiology), and excluding or intro- 

 ducing single factors (as oxygen, moisture, heat, and the like) 

 by suitable methods; 



(i) observing, and experimenting with, myriads of instances, 

 and continuing this for many years (as exemplified in Luther 

 Burbank's enquiries); and 



(y) proceeding by the law of averages and probability; 



(k) ascertaining whether the senses or the instruments are 

 at the time of investigation in normal condition; 



(/) following Descartes' injunction, and dividing, as far as 

 possible, complex problems into simple ones before investigating 

 them; and 



(m) isolating objects and forces, phases and circumstances, 

 utilising here Mill's Canons of Difference and Residue (as in 

 the experimental determination of food-stuffs necessary to plants 

 or animals); 1 



(ri) aiming at the ideally simple and minimal in thought, 

 movement, energy, means, material, conclusion, and statement 

 (e.g., the use of mercury instead of water in the barometer, 

 the tonic solfa notation, the continuous twenty-four hours' 

 system of measurement, summing the zeros as in 7X10 23 , 

 furnishing percentages, establishing international index numbers 

 and units in all departments, romanising the Japanese and 

 Chinese alphabets, fountain pens, rustless steel for knives) ; and 



1 Professor Bateson, speaking of Abbe Mendel's experiments, says: "In 

 order to obtain a clear result he saw that it was absolutely necessary to 

 start with pure-breeding, homogeneous materials, to consider each character 

 separately, and on no account to confuse the different generations together." 

 (Mendel's Principles of Heredity, 1909, p. 7.) In this cautious manner Mendel 

 studied separately seven different characters of the pea, and his followers 

 have even excelled him in thoroughness. So, too, it was only after animals 

 were fed upon thoroughly purified proteins, fats, carbo-hydrates, and certain 

 mineral salts, that the need of other essential food factors became evident, 

 whilst, conversely, the addition of the latter produced a perfect diet. In 

 physical and mechanical enquiries it is common to assume a fact to be far 

 simpler than it is for the purpose of securing a point of departure. Hence 

 we read in mechanics of points, particles, rigid bodies, and perfect fluids. 

 When the solution for the idealised fact is obtained, less simple facts are 

 studied until, so far as possible, the fact is known in all its complexity. 

 That such is the procedure in geometry, with its perfect triangles, squares, 

 and circles, is a commonplace. The use of the magnetic needle in magnetic 

 experiments offers a further instance of circumventing the unnecessary com- 

 plexity which arises when ordinary magnetic substances are employed. 



The principle of the simplest case is involved in the principles of "least 

 effort", "the line of least resistance", "the law of parsimony", and in the 

 phrases "entities are not to be multiplied without necessity" (William of 

 Occam), and "no more natural causes are to be assumed than such as are 

 true and suffice to explain the phenomena" (Newton). (See a short article 

 on "The Simplicity of Natural Laws", by Dr. C. H. Desch, in The Positivist 

 Review, May, 1912.) 



20* 



