Introduction. 3 



built out of generalisations involved and complex in their 

 nature. Manifestly, therefore, if we accept this as a principle 

 of classification, the sciences will arrange themselves in order 

 of their difficulty. Further, the sciences dealing with gene- 

 ralities must precede those dealing with specialities, since the 

 latter are dependent on the former for proof. The science, 

 for instance, dealing with the subject of chemical decompo- 

 sition in general must precede the science which discusses 

 the phenomena of life, amongst which the laws of chemical 

 decomposition play so important a part. 



If the sciences be classified according to such principles, 

 they will be found, generally speaking, to arrange themselves 

 in the order of their own historic development. Naturally, 

 therefore, the classification will indicate the order in which 

 they ought to be studied. The absurdity of endeavouring 

 to grapple with the principles of Biology without a prelim- 

 inary acquaintance with the facts and laws of Physics and 

 Chemistry, for instance, becomes at once apparent ; nor will 

 the absurdity be diminished, and the misconceptions which 

 result be less pronounced and mischievous, when attempts 

 are made not only to become acquainted with, but even to 

 teach the principles of the higher sciences of Sociology and 

 Ethics without even an elementary knowledge of the facts 

 and conclusions of Biology. 



The most general of the sciences is manifestly Astro- 

 nomy, since it treats of the universe in the widest possible 

 acceptation of the term. Astronomy may be defined as the 

 science which discusses 'the distribution, motions and 

 characteristics of the heavenly bodies.' Astronomy requires 

 for its proper study an accurate and extensive knowledge of 

 qualitative and quantitative methods, but its conclusions are 

 independent of the special conclusions of the other sciences. 



The first limitation to the scope of scientific enquiry is, 

 naturally, accessibility to the subject matter of science. An 

 extensive acquaintance with matter so far removed as the 

 fixed stars, or even the planets of our own system, is amani- 



B 2 



