294 THE INDUCTIONS 6F BIOLOGY. 



simplicity. The first classifications are sure, therefore, to be 

 groupings of objects that resemble each other in external or 

 easily-perceived attributes, and attributes that are not of com- 

 plex characters. Those likenesses among things which are 

 due to their possession in common of simple obvious properties, 

 may or may not coexist with further likenesses among them. 

 When geometrical figures are classed as curvilinear and 

 rectilinear, or when the rectilinear are divided into trilateral, 

 quadrilateral, &c, the distinctions made, connote various 

 other distinctions, with which they are necessarily bound 

 up ; but if liquids be classed according to their visible cha- 

 racters — if water, alcohol, sulphuret of carbon, &c, be 

 grouped as colourless and transparent, we have things placed 

 together which are unlike in their essential natures. Thus, 

 where the objects classed have numerous attributes, the pro- 

 babilities are, that the early classifications, based on simple 

 and manifest attributes, unite under the same head many 

 objects that have no resemblances in the majority of their 

 attributes. As the knowledge of objects increases, it be- 

 comes possible to make groups of which the members have 

 more numerous properties in common ; and to ascertain what 

 property, or combination of properties, is most characteristic 

 of each group. And the classification eventually arrived at, 

 is one in which the segregation has been carried so far, that 

 the objects integrated in each group have more attributes in 

 common with one another, than they have in common with 

 any excluded objects ; one in which the groups of such groups 

 are integrated on the same principle ; and one in which the 

 degrees of differentiation and integration are proportioned to 

 the degrees of intrinsic unlikeness and likeness. And the 

 ultimate classification, while it serves most completely to 

 identify the things, serves also to express the greatest amount 

 of knowledge concerning the things — enables us to predicate 

 the greatest number of facts concerning each thing ; and by 

 so doing proves that it expresses the most precise corre- 

 spondence between our conceptions and the realities. 



