PART IIL INTRODUCTORY. 



1'imagination aussi nette et distincte, ou la memoire aussi ample 

 ou aussi presente, que quelques autres. Et je ne sache point 

 de qualites que celles-ci qui servent a la perfection de 1'esprit." 

 (Discours de la methode, 1668, second paragraph.) 



Kant says: "Two things chiefly are required in a philosopher 

 1. Cultivation of talents and skill, so as to use them for various 

 ends. 2. Readiness in the use of all means to any ends that 

 may be chosen. Both must be united." (Introduction to Logic, 

 London, 1895, p. 16.) 



Charles Darwin expressed himself thus: "I think I am superior 

 to the common run of men in noticing things which easily 

 escape attention, and in observing them carefully. From my 

 earliest youth I have had the strongest desire to understand 

 or explain everything I observed that is, to group all facts 

 under some general laws." (Frank Cramer, op. cit., p. 29.) 



Bain particularises: "To possess the mind of a large store 

 of the related facts; often to refresh the recollection of them; 

 to come into frequent contact with objects that seem likely to 

 afford comparisons and analogies; not to stand too near at one 

 set of facts so as to be overpowered by their specialities; not 

 to be engrossed with the work of observing the facts; and, in 

 general, as of matters of great difficulty, to keep the mind 

 free from attitudes and pursuits antagonistic to the end in 

 view." (Logic, vol. 2, p. 415.) 



La logique, ou I'art de penser, 1662, contains a section entitled "La 

 methode des sciences reduite a huit regies principales". 



Spinoza formulated the following rules for the conduct of the under- 

 standing: "(1) There is the knowledge which we derive from hearing or 

 from some arbitrary sign. (2) There is the knowledge which we derive 

 from vague experience. ... (3) There is the knowledge which arises when 

 the essence of a thing is deduced from another thing, but not adequate- 

 ly. ... (4) Finally, there is the knowledge which arises when a thing 

 is perceived through its essence alone, or through the knowledge of its 

 proximate cause." (Tractatus de Intellectus Emendations, London, 1895, 

 pp. 9-10.) 



Leibniz submits the following rules referring to the art of invention: 

 "(1) To know a thing, one must take into account all the requisites 

 ('requisits') of the thing, that is, everything necessary to distinguish it 

 from everything else. This we may name definition,, nature, reciprocal 

 property. (2) Apply the rule to each condition, or requisite, that enters 

 into the definition which has been found, and look for the requisite of 

 each requisite. (3) When the analysis has been pushed to the end, the 

 perfect knowledge of the thing proposed has been reached." (Couturat, 

 La logique de Leibnitz, p. 181.) 



Kant has sundry allusions to practical scientific rules. According to 

 him, "Logic is not a general art of discovery nor an organon of truth; 

 it is not an algebra by help of which hidden truths may be discovered". 

 (Introduction to Logic, 1895, p. 10.) He claims that the "general rules 

 and conditions of the avoidance of error are (1) to think oneself; (2) to 

 put oneself in thought in the place or point of view of another; and 

 (3) always to think consistently. The first may be called enlightened; 

 the second enlarged; and the third consequent or coherent thinking". 

 (Ibid., p. 48.) Kant furnishes eight further practical rules (pp. 33-34) 

 which, for want of space, we cannot quote. 



